CD69
Early activation antigen CD69 (Activation inducer molecule) (AIM) (BL-AC/P26) (C-type lectin domain family 2 member C) (EA1) (Early T-cell activation antigen p60) (GP32/28) (Leukocyte surface antigen Leu-23) (MLR-3) (CD69 antigen) [CLEC2C]
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CD4 regulatory T cells have been intensively studied during aging, but little is still known about age-related changes of other regulatory T cell subsets. It was, therefore, the goal of the present study to analyze CD8 human leukocyte antigen-antigen D related (HLADR) T cells in old age, a cell population reported to have suppressive activity and to be connected to specific genetic variants. We demonstrate a strong increase in the number of CD8 HLADR T cells with age in a cohort of female Sardinians as well as in elderly male and female persons from Austria. We also show that CD8 HLADR T cells lack classical activation molecules, such as CD69 and CD25, but contain increased numbers of checkpoint inhibitory molecules, such as cytotoxic T lymphocyte-associated antigen 4, T cell immunoglobulin and mucin protein-3, LAG-3, and PD-1, when compared with their HLADR counterparts. They also have the capacity to inhibit the proliferation of autologous peripheral blood mononuclear cells. This suppressive activity is, however, decreased when CD8 HLADR T cells from elderly persons are analyzed. In accordance with this finding, CD8 HLADR T cells from persons of old age contain lower percentages of checkpoint inhibitory molecules than young controls. We conclude that in spite of high abundance of a CD8 regulatory T cell subset in old age its expression of checkpoint inhibitory molecules and its suppressive function on a per cell basis are reduced. Reduction of suppressive capacity may support uncontrolled subclinical inflammatory processes referred to as "inflamm-aging."
MeSH Terms
- Adolescent
- Adult
- Aged
- Aged, 80 and over
- Aging
- Antigens, CD
- Austria
- CD8 Antigens
- CTLA-4 Antigen
- Cell Proliferation
- Cohort Studies
- Female
- HLA-DR Antigens
- Hepatitis A Virus Cellular Receptor 2
- Humans
- Immune Tolerance
- Inflammation
- Italy
- Lymphocyte Activation
- Male
- Middle Aged
- Programmed Cell Death 1 Receptor
- T-Lymphocytes, Regulatory
- Young Adult
Keywords
- CD8 T cells
- CD8 human leukocyte antigen–antigen D related
- aging
- checkpoint inhibitory molecules
- regulatory T cells
Preliminary evidence suggests that premature immunosenescence is involved in bipolar disorder (BD) pathophysiology. The cellular marker CD69 is expressed in T lymphocyte surface during their activation and its expression is negatively correlated with age. The objective of this study was to assess the moderating effects of obesity on the reduction of expression of CD69, a marker of immunosenescence. Forty euthymic patients with BD type I, aged 18-65 years, were included in this study. The healthy comparison group consisted of 39 volunteers who had no current or lifetime history of mental disorders, no use of psychotropic medications, and no known family history of mood disorders or psychosis. Peripheral blood mononuclear cells from BD patients and healthy controls were collected and isolated. The cells were allowed to grow in culture and stimulated for 3 days. CD69 was marked and read in flow cytometry. We found that the lower expression of CD69 in BD patients was moderated by body mass index (BMI) in both CD4 (RR = 0.977, 95% CI 0.960-0.995, [i]p[/i] = 0.013) and CD8 cells (RR = 0.972, 95% CI 0.954-0.990, [i]p[/i] = 0.003). Our findings indicate that BMI could potentially influence the process of premature aging in BD.
Keywords
- Bipolar disorder
- CD69
- Immunosenescence
- Inflammation
- Obesity
- T cell activation
The study aims to generate an immunological age (IA) trait on the basis of immune cell differentiation parameters, and to test whether the IA is related to age and disease characteristics. Forty-four euthymic type I bipolar disorder patients were included in this study. Five immunosenescence-related parameters were assessed: proportions of late-differentiated cells (e.g., CD3 CD8 CD28-CD27- and CD3-CD19 IgD-CD27-), and the expression of CD69, CD71, and CD152 after stimulation. Confirmatory factor analysis was applied to generate an IA trait underling the 5 measures. The best-fit model was constituted by 4 parameters that were each related to an underlying IA trait, with 1 cell population positively correlated (CD3 CD8 CD28-CD27- [λ = 0.544, where λ represents the loading of the parameter onto the IA trait] and 3 markers negatively correlated (CD69 [λ = -0.488], CD71 [λ = -0.833], and CD152 [λ = -0.674]). The IA trait was associated with chronological age (β = 0.360, p = .013) and the number of previous mood episodes (β = 0.426, p = .006). In a mediation model, 84% of the effect between manic episodes, and IA was mediated by body mass index. In bipolar disorder type I, premature aging of the immune system could be reliably measured using an index that validated against chronological age, which was related to adverse metabolic effects of the disease course.
MeSH Terms
- Adolescent
- Adult
- Aging, Premature
- Biomarkers
- Bipolar Disorder
- Factor Analysis, Statistical
- Female
- Humans
- Immunosenescence
- Male
- Middle Aged
- Young Adult
Keywords
- aging
- bipolar
- confirmatory factor analysis
- neuroimmunology
Toxic shock syndrome (TSS) is capable of inducing life-threatening fever, rash, and systemic organ failure, though the specific mechanisms behind these symptoms remain poorly understood. Staphylococcal enterotoxin B (SEB) and other superantigens have shown to be important factors in TSS, capable of promoting cross-linking between T cell receptors and major histocompatibility complexes which results in overwhelming T cell activation, proliferation, and cytokine production. The resulting proinflammatory cytokine cascade, often referred to as the "cytokine storm," seems to be critical to the development of disease. Interestingly, clinical studies have shown that children exhibit less severe TSS-associated morbidity than adults, though the mechanism behind this phenomenon has not been addressed. Indeed, despite the fact that most novel antigen exposure occurs early in life, be it from environmentally acquired pathogens or routine vaccination, normal pediatric T cell immune functions remain critically underexplored. This is largely due to difficulty in obtaining enough samples to explore more than a narrow sliver of the cell-mediated immune compartment. To address this limitation, we optimized a T effector (T )/circulating T follicular helper (cT ) cell mass cytometry panel which allowed us to analyze a wide array of T cell populations and effector functions following [i]in vitro[/i] SEB stimulation. We show that T cell activation-as measured by CD69 expression-following SEB stimulation is lower in pediatric participants, increasing throughout childhood, and reaching adult levels by around 15 years old. Further, while individual CD4 effector memory T cell (T ) effector molecules show limited age-associated differences following SEB stimulation, multifunctional CD4 T are shown to positively correlate with increasing age through adolescence. Individual CD8 T effectors and multifunctional phenotypes also show very strong age-associated increases following SEB stimulation. SEB stimulation has little impact on cT activation or functional cellular markers, regardless of age. These results, coupled with the fact that a robust proinflammatory cytokine response seems critical to developing severe TSS, suggest a possible connection between the significantly reduced T cell activation and multifunctional populations following [i]in vitro[/i] SEB stimulation in our pediatric participants and clinical observations relating to reduced TSS mortality in children.
MeSH Terms
- Adolescent
- Adult
- Aged
- Aging
- CD8-Positive T-Lymphocytes
- Child
- Enterotoxins
- Female
- Humans
- Lymphocyte Activation
- Male
- Middle Aged
- T-Lymphocytes, Helper-Inducer
Keywords
- T cell response
- dimensionality reduction
- mass cytometry
- multifunctionality
- pediatric immunology
- staphylococcal enterotoxin B
- toxic shock syndrome
Studies in clinical and aging populations support associations between immunological function, cognition and mood, although these are not always in line with animal models. Moreover, very little is known about the relationship between immunological measures and cognition in healthy young adults. The present study tested associations between the state of immune system and memory recall in a group of relatively healthy adults. Immediate and delayed memory recall was assessed in 30 participants using the computerised cognitive battery. CD4, CD8 and CD69 subpopulations of lymphocytes, Interleukin-6 (IL-6) and cortisol were assessed with blood assays. Correlation analysis showed significant negative relationships between CD4 and the short and long delay memory measures. IL-6 showed a significant positive correlation with long-delay recall. Generalized linear models found associations between differences in all recall challenges and CD4. A multivariate generalized linear model including CD4 and IL-6 exhibited a stronger association. Results highlight the interactions between CD4 and IL-6 in relation to memory function. Further study is necessary to determine the underlying mechanisms of the associations between the state of immune system and cognitive performance.
MeSH Terms
- Adolescent
- Adult
- Aging
- Animals
- CD4-Positive T-Lymphocytes
- CD8-Positive T-Lymphocytes
- Female
- Humans
- Hydrocortisone
- Interleukin-6
- Killer Cells, Natural
- Male
- Memory, Long-Term
- Memory, Short-Term
- Middle Aged
- Reference Values
- Statistics as Topic
- Young Adult
Keywords
- CD4
- Immunological measures
- Interleukin-6
- Memory
- T lymphocytes
The incidence and severity of herpes zoster (HZ) increases with age. The live attenuated zoster vaccine generates immune responses similar to HZ. We compared the immune responses to zoster vaccine in young and older to adults to increase our understanding of the immune characteristics that may contribute to the increased susceptibility to HZ in older adults. Young (25-40 y; [i]n[/i] = 25) and older (60-80 y; [i]n[/i] = 33) adults had similar magnitude memory responses to varicella-zoster virus (VZV) ex vivo restimulation measured by responder cell-frequency and flow cytometry, but the responses were delayed in older compared with young adults. Only young adults had an increase in dual-function VZV-specific CD4 and CD8 T cell effectors defined by coexpression of IFN-γ, IL-2, and CD107a after vaccination. In contrast, older adults showed marginal increases in VZV-specific CD8 CD57 senescent T cells after vaccination, which were already higher than those of young adults before vaccination. An increase in VZV-stimulated CD4 CD69 CD57 PD1 and CD8 CD69 CD57 PD1 T cells from baseline to postvaccination was associated with concurrent decreased VZV-memory and CD8 effector responses, respectively, in older adults. Blocking the PD1 pathway during ex vivo VZV restimulation increased the CD4 and CD8 proliferation, but not the effector cytokine production, which modestly increased with TIM-3 blockade. We conclude that high proportions of senescent and exhausted VZV-specific T cells in the older adults contribute to their poor effector responses to a VZV challenge. This may underlie their inability to contain VZV reactivation and prevent the development of HZ.
MeSH Terms
- Adult
- Age Factors
- Aged
- Aged, 80 and over
- Aging
- Antibodies, Viral
- CD4-Positive T-Lymphocytes
- CD8-Positive T-Lymphocytes
- Female
- Herpes Zoster Vaccine
- Herpesvirus 3, Human
- Humans
- Immunity, Cellular
- Immunologic Memory
- Interferon-gamma
- Interleukin-2
- Lysosomal-Associated Membrane Protein 1
- Male
- Middle Aged
- Programmed Cell Death 1 Receptor
- Vaccination
- Young Adult
Recognition of tumor cells by the immune system is a key step in cancer eradication. Melphalan is an alkylating agent routinely used in the treatment of patients with multiple myeloma (MM), but at therapeutic doses it leads to an immunosuppressive state due to lymphopenia. Here, we used a mouse model of MM to investigate the ability of [i]in vivo[/i] treatment with low doses of melphalan to modulate natural killer (NK) cell activity, which have been shown to play a major role in the control of MM growth. Melphalan treatment was able to enhance the surface expression of the stress-induced NKG2D ligands RAE-1 and MULT-1, and of the DNAM-1 ligand PVR (CD155) on MM cells, leading to better tumor cell recognition and killing by NK cells, as highlighted by NK cell increased degranulation triggered by melphalan-treated tumor cells. Remarkably, NK cell population was not affected by the melphalan dose used, but rather displayed activation features as indicated by CD107a and CD69 expression. Furthermore, we showed that low doses of melphalan fail to induce tumor cell apoptosis, but promote the [i]in vivo[/i] establishment of a senescent tumor cell population, harboring high levels of the stress-induced ligands RAE-1 and PVR. Taken together our data support the concept of using chemotherapy in order to boost antitumor innate immune responses and report the possibility to induce cellular senescence of tumor cells [i]in vivo[/i].
Keywords
- DNAM-1
- NKG2D
- immunomodulation
- melphalan
- multiple myeloma
- natural killer cell
- senescence
Regulatory T cells (Tregs), a subset of CD4( ) T cells, dramatically accumulate with age in humans and mice and contribute to age-related immune suppression. Recently, we showed that a majority of accumulating Tregs in aged mice expressed low levels of CD25, and their accrual is associated with declining levels of IL-2 in aged mice. In this study, we further investigated the origin of CD25(lo) Tregs in aged mice. First, aged Tregs had high expression of neuropilin-1 and Helios, and had a broad Vβ repertoire. Next, we analyzed the gene expression profile of Tregs, naive T cells, and memory T cells in aged mice. We found that the gene expression profile of aged CD25(lo) Tregs were more related to young CD25(lo) Tregs than to either naive or memory T cells. Further, the gene expression profile of aged Tregs was consistent with recently described "effector" Tregs (eTregs). Additional analysis revealed that nearly all Tregs in aged mice were of an effector phenotype (CD44(hi)CD62L(lo)) and could be further characterized by high levels of ICOS and CD69. ICOS contributed to Treg maintenance in aged mice, because in vivo Ab blockade of ICOSL led to a loss of eTregs, and this loss was rescued in Bim-deficient mice. Further, serum levels of IL-6 increased with age and contributed to elevated expression of ICOS on aged Tregs. Finally, Treg accrual was significantly blunted in aged IL-6-deficient mice. Together, our data show a role for IL-6 in promoting eTreg accrual with age likely through maintenance of ICOS expression.
MeSH Terms
- Aging
- Animals
- Antigens, CD
- Antigens, Differentiation, T-Lymphocyte
- Apoptosis Regulatory Proteins
- Base Sequence
- Bcl-2-Like Protein 11
- Cell Death
- Cell Survival
- DNA-Binding Proteins
- Gene Expression Profiling
- Hyaluronan Receptors
- Immunologic Memory
- Inducible T-Cell Co-Stimulator Ligand
- Inducible T-Cell Co-Stimulator Protein
- Interleukin-2 Receptor alpha Subunit
- Interleukin-6
- L-Selectin
- Lectins, C-Type
- Membrane Proteins
- Mice
- Mice, Inbred C57BL
- Mice, Knockout
- Neuropilin-1
- Proto-Oncogene Proteins
- Sequence Analysis, DNA
- T-Lymphocytes, Regulatory
- Transcription Factors
With increasing age, naive CD4 T cells acquire intrinsic defects that compromise their ability to respond and differentiate. Type I IFNs, pervasive constituents of the environment in which adaptive immune responses occur, are known to regulate T cell differentiation and survival. Activated naive CD4 T cells from older individuals have reduced responses to type I IFN, a defect that develops during activation and that is not observed in quiescent naive CD4 T cells. Naive CD4 T cells from young adults upregulate the expression of STAT1 and STAT5 after activation, lowering their threshold to respond to type I IFN stimulation. The heightened STAT signaling is critical to maintain the expression of CD69 that regulates lymphocyte egress and the ability to produce IL-2 and to survive. Although activation of T cells from older adults also induces transcription of STAT1 and STAT5, failure to exclude SHP-1 from the signaling complex blunts their type I IFN response. In summary, our data show that type I IFN signaling thresholds in naive CD4 T cells after activation are dynamically regulated to respond to environmental cues for clonal expansion and memory cell differentiation. Naive CD4 T cells from older adults have a defect in this threshold calibration. Restoring their ability to respond to type I IFN emerges as a promising target to restore T cell responses and to improve the induction of T cell memory.
MeSH Terms
- Adult
- Aged
- Aged, 80 and over
- Aging
- Antigens, CD
- Antigens, Differentiation, T-Lymphocyte
- CD4-Positive T-Lymphocytes
- Cell Differentiation
- Female
- Humans
- Interferon Type I
- Interleukin-2
- Lectins, C-Type
- Lymphocyte Activation
- Male
- Protein Tyrosine Phosphatase, Non-Receptor Type 6
- Receptor, Interferon alpha-beta
- STAT1 Transcription Factor
- STAT5 Transcription Factor
- Young Adult
HIV-infected individuals suffer from accelerated immunologic aging. One of the most prominent changes during T lymphocyte aging is the accumulation of CD28(null) T lymphocytes, mainly CD8( ) but also CD4( ) T lymphocytes. Enhancing the functional properties of these cells may be important because they provide antigen-specific defense against chronic infections. The objective of this study was to compare the responses of CD4( )CD28(null) and CD8( )CD28(null) T lymphocytes from HIV-infected patients to the immunomodulatory effects of cytokines IL-15 and IL-21. We quantified the frequencies of CD4( )CD28(null) and CD8( )CD28(null) T lymphocytes in peripheral blood from 110 consecutive, HIV-infected patients and 25 healthy controls. Patients showed increased frequencies of CD4( )CD28(null) and CD8( )CD28(null). Both subsets were positively correlated to each other and showed an inverse correlation with the absolute counts of CD4( ) T lymphocytes. Higher frequencies of HIV-specific and CMV-specific cells were found in CD28(null) than in CD28( ) T lymphocytes. Activation of STAT5 by IL-15 and STAT3 by IL-21 was higher in CD28(null) compared with CD28( ) T lymphocytes. Proliferation, expression of CD69, and IFN-γ production in CD28(null) T lymphocytes were increased after treatment with IL-15, and IL-21 potentiated most of those effects. Nevertheless, IL-21 alone reduced IFN-γ production in response to anti-CD3 stimulation but increased CD28 expression, even counteracting the inhibitory effect of IL-15. Intracytoplasmic stores of granzyme B and perforin were increased by IL-15, whereas IL-21 and simultaneous treatment with the 2 cytokines also significantly enhanced degranulation in CD4( )CD28(null) and CD8( )CD28(null) T lymphocytes. IL-15 and IL-21 could have a role in enhancing the effector response of CD28(null) T lymphocytes against their specific chronic antigens in HIV-infected patients.
MeSH Terms
- Adult
- Antigens, CD
- Antigens, Differentiation, T-Lymphocyte
- CD28 Antigens
- CD4-Positive T-Lymphocytes
- CD8-Positive T-Lymphocytes
- Cell Degranulation
- Cell Proliferation
- Cohort Studies
- Demography
- Female
- Granzymes
- HIV Antigens
- HIV Infections
- Humans
- Interferon-gamma
- Interleukin-15
- Interleukins
- Lectins, C-Type
- Male
- Middle Aged
- Perforin
- STAT3 Transcription Factor
- STAT5 Transcription Factor
- Tumor Suppressor Proteins
- Up-Regulation
- Young Adult
Keywords
- T lymphocyte differentiation
- cytotoxicity
- immunosenescence
Several plant extracts, including certain polyphenols, prime innate lymphocytes and enhance responses to secondary stimuli. Oenothein B, a polyphenol isolated from Epilobium angustifolium and other plant sources, enhances IFNγ production by both bovine and human NK cells and T cells, alone and in response to secondary stimulation by cytokines or tumor cells. Innate immune cell responsiveness is known to be affected by aging, but whether polyphenol responses by these cells are also impacted by aging is not known. Therefore, we examined oenothein B responsiveness in T cells from cord blood, young, and adult donors. We found that oenothein B stimulates bovine and human T cells from individuals over a broad range of ages, as measured by increased IL-2Rα and CD69 expression. However, clear differences in induction of cytokine production by T cells were seen. In T cells from human cord blood and bovine calves, oenothein B was unable to induce IFNγ production. However, oenothein B induced IFNγ production by T cells from adult humans and cattle. In addition, oenothein B induced GM-CSF production by human adult T cells, but not cord blood T cells. Within the responsive T cell population, we found that CD45RO memory T cells expressed more cytokines in response to oenothein B than CD45RO- T cells. In summary, our data suggest that the immunostimulation of T cells by oenothein B is influenced by age, particularly with respect to immune cytokine production.
MeSH Terms
- Adult
- Aging
- Animals
- Antigens, CD
- Antigens, Differentiation, T-Lymphocyte
- Cattle
- Epilobium
- Fetal Blood
- Humans
- Hydrolyzable Tannins
- Immunity, Cellular
- Immunologic Memory
- Infant, Newborn
- Interferon-gamma
- Interleukin-2 Receptor alpha Subunit
- Killer Cells, Natural
- Lectins, C-Type
- T-Lymphocytes
Keywords
- Bovine
- GM-CSF
- Human
- Interferon-γ
- Memory T cells
- Polyphenol
The reciprocal activation of dendritic cells (DCs) and natural killer cells (NKs) plays a key role in both innate and adaptive immunity. The effect of aging on this cross-talk, a critical step in virus disease control and tumor immunology, has not been reported. Splenic DCs and NKs were purified from both young and old C57BL/6 mice and cocultured in the presence of polyinosinic:polycytidylic acid (poly I:C). The resulting activation of NKs was measured as expression of CD69 and secretion of IFN-γ. However, DCs from old mice could not activate NKs from either young or old mice in vitro or in vivo. In contrast, DCs from young mice efficiently activated NKs from both young and old mice. DCs from old mice were deficient in poly I:C-stimulated secretion of IL-15, IL-18, and IFN-α. Gene expression analysis revealed many other differences between DCs of old and young mice. Young mice strongly eradicated MHC class I-negative NK-sensitive RMA-S lymphoma mutant tumor cells, but old mice did not, in concert with the previous report that mousepox kills aged, but not young, C57BL/6 mice. Furthermore, a similar dysfunction of DC and its key role in NK activation was found in 27 out of 55 healthy human donors.
MeSH Terms
- Adult
- Aged
- Aging
- Animals
- Cell Line, Tumor
- Coculture Techniques
- Cytokines
- Dendritic Cells
- Humans
- Interferon Inducers
- Interferon-gamma
- Killer Cells, Natural
- Lymphocyte Activation
- Mice
- Mice, Inbred C57BL
- Mice, Transgenic
- Middle Aged
- Neoplasms, Experimental
- Poly I-C
Keywords
- IL-12
- cytokines
- interferon-alpha
- microarray
- volcano plot
T cell-dependent B-cell responses decline with age, indicating declined cognate helper activity of aged CD4 T cells for B cells. However, the mechanisms remain unclear. T follicular helper (Tfh) cells, a novel T helper subset, play an essential role in helping B cells differentiation into long-lived plasma cells in germinal center (GC) or short-lived plasma cells. In the present study, we proposed that there might existe changes of proportion, phenotype or cytokine production of blood Tfh cells in healthy elderly individuals compared with healthy young individuals. The results showed that frequencies of aged blood CXCR5 CD4 Tfh cells increased compared with young subjects. Both aged and young blood CXCR5 CD4 Tfh cells constitutively expressed CD45RO, CCR7 and CD28, and few of these cells expressed CD69 or HLA-DR, which indicated that they were resting memory cells. There was no significant difference of IL-21 frequency production by aged blood CXCR5 CD4 Tfh determined by FACS compared with young individuals, however, aged PBMCs produced significantly higher levels of IL-21 evaluated by ELISA. Furthermore, there were no significant differences of percentages of IFN-γ, IL-4, IL-17 or IL-22 production by aged Tfh cells compared with their counterparts of young individuals respectively. However, frequencies of IL-17 cells within aged CD4 CXCR5-T cells were markedly lower than in the young individuals. Furthermore we observed different frequencies of IFN-γ, IL-17, IL-4 or IL-22 production by Tfh or by CD4 CXCR5- cells in aged and young subjects respectively. Our data demonstrated that the frequencies of blood memory CXCR5 CD4 Tfh cells increased in the elderly population. There were similar frequencies of Th characterized cytokine production such as IL-21, IFN-γ, IL-4, IL-17 or IL-22 in aged and young Tfh cells. However, aged PBMCs produced a significantly higher amount of IL-21 compare to young subjects.
Keywords
- Aging
- IL-21
- Tfh cells
Systemic sclerosis (SSc) is a chronic disease, with early activation of the immune system. The aim of our work was to address how SSc-mesenchymal stem cells (MSCs), although senescent, might preserve specific immunomodulatory abilities during SSc. MSCs were obtained from 10 SSc patients and 10 healthy controls (HC). Senescence was evaluated by assessing cell cycle, β-galactosidase (β-Gal) activity, p21 and p53 expression; doxorubicin was used as acute senescence stimulus to evaluate their ability to react in stressed conditions. Immunomodulatory abilities were studied co-culturing MSCs with peripheral blood mononuclear cells (PBMCs) and CD4( ) cells, in order to establish both their ability to block proliferation in mixed lymphocyte reaction and in regulatory T cells (Tregs) induction. SSc-MSC showed an increase of senescence biomarkers. Eighty per cent of MSCs were in G0-G1 phase, without significant differences between SSc and HC. SSc-MSCs showed an increased positive β-Gal staining and higher p21 transcript level compared to HC cells. After doxorubicin, β-Gal staining increased significantly in SSc-MSCs. On the contrary, doxorubicin abolished p21 activation and elicited p53 induction both in SSc- and HC-MSCs. Interleukin (IL)-6 and transforming growth factor (TGF)-β-related transcripts and their protein levels were significantly higher in SSc-MSCs. The latter maintained their immunosuppressive effect on lymphocyte proliferation and induced a functionally regulatory phenotype on T cells, increasing surface expression of CD69 and restoring the regulatory function which is impaired in SSc. Increased activation of the IL-6 pathway observed in our cells might represent an adaptive mechanism to senescence, but preserving some specific cellular functions, including immunosuppression.
MeSH Terms
- Antigens, CD
- Antigens, Differentiation, T-Lymphocyte
- Cell Proliferation
- Cell- and Tissue-Based Therapy
- Cells, Cultured
- Cellular Senescence
- Coculture Techniques
- Cyclin-Dependent Kinase Inhibitor p21
- Doxorubicin
- Humans
- Immunomodulation
- Interleukin-6
- Lectins, C-Type
- Mesenchymal Stem Cells
- Scleroderma, Systemic
- T-Lymphocytes, Regulatory
- Transforming Growth Factor beta
- Tumor Suppressor Protein p53
- beta-Galactosidase
Keywords
- immunomodulatory abilities
- mesenchymal stem cells
- senescence
- systemic sclerosis
Aging is associated with altered immune responses, particularly with a diminished CD8 T cell response. Although both intrinsic and extrinsic factors are hypothesized to impact this decreased T cell response, the direct evidence of an intrinsic deficiency in virus-specific CD8 T cells is limited. In this study, a TCR transgenic (Tg) P14 mouse model was utilized to compare the activation and proliferation of the Tg CD8 T cells of young and aged P14 mice upon stimulation with antigen or infection with virus. The proliferation of purified Tg CD8 T cells of aged mice was significantly lower than that of young mice when cultured in vitro with both the LCMV specific peptide and antigen presenting cells from young wild type mice. In addition, expression of the activation markers, CD69, CD25, and CD44, was delayed on Tg T cells of aged mice after stimulation. Importantly, while adoptive transfer of purified Tg CD8 T cells of young or aged mice into young wild type mice resulted in expansion of the Tg CD8 T cells of both ages after LCMV infection, the expansion of the Tg T cells from aged mice was significantly decreased compared with that of the Tg T cells from young mice. However, while the number of IFN-γ secreting Tg CD8 T cells from aged mice was significantly decreased compared to that of young mice, the percentages of Tg CD8 T cells producing IFN-γ were similar in young and aged mice, demonstrating that proliferation, but not function, of the Tg CD8 T cells of aged mice was impaired. Importantly, chronological age alone was not sufficient to predict an altered proliferative response; rather, expression of high levels of CD44 on CD8 T cells of aged mice reflected a decreased proliferative response. These results reveal that alterations intrinsic to CD8 T cells can contribute to the age-associated defects in the primary CD8 T cell response during viral infection.
MeSH Terms
- Adoptive Transfer
- Aging
- Animals
- CD8-Positive T-Lymphocytes
- Cell Proliferation
- Cells, Cultured
- Disease Models, Animal
- Immunity, Cellular
- Immunity, Innate
- Lymphocytic Choriomeningitis
- Lymphocytic choriomeningitis virus
- Mice
- Mice, Transgenic
- Spleen
Understanding the immune responses that explain why infants require multiple doses of pertussis vaccine to achieve protection against infection is a high priority. The objective of this study was to compare the function and phenotypes of antigen-specific CD4( ) T cells in adults (n=12), compared to infants (n=20), following vaccination with acellular pertussis (DTaP) vaccine. Peripheral blood mononuclear cells (PBMCs) were stimulated with pertussis toxoid (PT), pertactin (PRN) and filamentous haemagglutinin (FHA). Multi-parameter flow cytometry was used to delineate CD4( ) T cell populations and phenotypes producing interferon (IFN)-γ, interleukin (IL)-2, tumour necrosis factor (TNF)-α and IL-4. Based on surface CD69 expression, infants demonstrated activation of vaccine antigen-specific CD4( ) T cells similar to adults. However, among infants, Boolean combinations of gates suggested that type 1 (Th-1) CD4( ) T cell responses were confined largely to TNF-α( ) IL-2( ) IFN-γ(-) or TNF-α( ) IL-2(-) IFN-γ(-) . A significantly lower percentage of polyfunctional T helper type 1 (Th1) responses (TNF-α( ) IFN-γ( ) IL-2( ) ) and type 2 (Th2) responses (IL-4) were present in the infants compared to adults. Moreover, a significantly higher percentage of infants' functional CD4( ) T cells were restricted to CD45RA(-) CCR7( ) CD27( ) phenotype, consistent with early-stage differentiated pertussis-specific memory CD4( ) T cells. We show for the first time that DTaP vaccination-induced CD4( ) T cells in infants are functionally and phenotypically dissimilar from those of adults.
MeSH Terms
- Adult
- Aging
- Antibodies, Bacterial
- Antigens, Bacterial
- Antigens, CD
- Antigens, Differentiation, T-Lymphocyte
- Bordetella pertussis
- CD4-Positive T-Lymphocytes
- Diphtheria-Tetanus-acellular Pertussis Vaccines
- Enterotoxins
- Female
- Humans
- Immunophenotyping
- Infant
- Lectins, C-Type
- Lymphocyte Activation
- Lymphokines
- Male
- T-Lymphocyte Subsets
- Th1 Cells
- Th2 Cells
- Vaccination
Physiological aging is accompanied by a marked reduction in natural killer (NK) cell cytotoxicity (NKCC) at the single cell level, but the underlying mechanisms are unknown. To address this issue, we isolated NK cells from healthy young (≤ 35 years) and old (≤ 60 years) subjects and examined the effect of age on events fundamental to the process of NKCC. Simultaneous assessment of NKCC and NK cell-target cell conjugate formation revealed a marked age-associated decline in NK cell killing but comparable conjugate formation, indicating a post-target cell binding defect was responsible for impaired NKCC. Despite a reduction in the proportion of NK cells expressing the activatory receptor NKp46, NK cells from old donors were not hyporesponsive to stimulation, as no age-associated difference was observed in the expression of the early activation marker CD69 following target cell coculture. Furthermore, intracellular levels of the key cytotoxic effector molecules perforin and granzyme B, and the fusion of secretory lysosomes with the NK cell membrane were also similar between the two groups. However, when we examined the binding of the pore-forming protein perforin to the surface of its target cell, an event that correlated strongly with target cell lysis, we found the percentage of perforin positive target cells was lower following coculture with NK cells from old subjects. Underlying this reduction in binding was an age-associated impairment in perforin secretion, which was associated with defective polarization of lytic granules towards the immunological synapse. We propose that reduced perforin secretion underlies the reduction in NKCC that accompanies physiological aging.
MeSH Terms
- Adult
- Aged
- Aging
- Apoptosis
- Cell Death
- Cell Degranulation
- Cytotoxicity, Immunologic
- Flow Cytometry
- Humans
- Immunological Synapses
- K562 Cells
- Killer Cells, Natural
- Leukocytes, Mononuclear
- Lymphocyte Activation
- Perforin
- Receptors, Natural Killer Cell
- Young Adult
Schnurri (Shn)-2 is a large zinc finger-containing protein implicated in cell growth, signal transduction and lymphocyte development. Here, we report that Shn-2-deficient (Shn-2(-/-)) mice develop CD3-positive lymphoma spontaneously. In Shn-2(-/-) mice, we observed decreased cytotoxicity of natural killer (NK) cells accompanied by decreased expression of perforin and granzyme-B. In addition, phosphorylation of signal transducer and activator of transcription (STAT) 5 was reduced in Shn-2(-/-) NK cells, while phosphorylation of STAT3 and protein expression of nuclear factor-κB p65 subunit were enhanced in Shn-2(-/-) NK cells. Moreover, cell-surface expression of activation molecules such as CD27, CD69 and CD122 were decreased on Shn-2(-/-) NK cells. Thus, Shn-2 is considered to play an important role in the activation and function of NK cells and the development of T cell lymphoma in vivo.
MeSH Terms
- Animals
- CD3 Complex
- Cytotoxicity, Immunologic
- DNA-Binding Proteins
- Granzymes
- Immunity, Innate
- Immunologic Surveillance
- Interleukin-2
- Killer Cells, Natural
- Longevity
- Lung
- Lymphocyte Activation
- Lymphoma, T-Cell
- Mice
- Mice, Inbred BALB C
- Mice, Knockout
- Neoplasm Proteins
- Perforin
- Specific Pathogen-Free Organisms
- Spleen
While it has been established that Treg cells can down-modulate an immune response, no study has addressed if the observed increase in Treg cells in aged mice is related to the decreased and delayed specific CD8 T cell responses seen following primary influenza infection. In this study, phenotypic characteristics and function of Treg cells were analyzed in young (4-6 months) and aged (18-22 months) mice prior to and during the course of primary influenza infection. Upon infection, aged, but not young, mice have a significant expansion of Treg cells. In addition, Treg cells of aged mice demonstrate both a higher percentage and higher expression per cell of CD69 both at baseline and during infection compared to young mice. However, Treg cells isolated from young and aged mice comparably suppress CD8 T cells and suppression is dose dependent. These results suggest that the increase in the percentage of Treg cells in aged mice may contribute to the diminished CD8 T cell response to primary influenza infection.
MeSH Terms
- Aging
- Animals
- Antigens, CD
- Antigens, Differentiation, T-Lymphocyte
- CD8-Positive T-Lymphocytes
- Disease Models, Animal
- Forkhead Transcription Factors
- Interleukin-2 Receptor alpha Subunit
- Lectins, C-Type
- Mice
- Mice, Inbred BALB C
- Mice, Inbred C57BL
- Mice, Transgenic
- Orthomyxoviridae Infections
- Phenotype
- Spleen
- T-Lymphocytes, Regulatory
- Time Factors
The abundance of a preselection of transcripts involved in inflammation, immunosenescence and stress response was compared between PBMC of healthy aged donors and aged patients in acute phase of heart failure and at recovery. This study identified 22 transcripts differentially abundant in acute phase of heart failure versus healthy aged subjects. Transcripts involved in inflammation and oxidative stress were more abundant. Those associated with T-cell functions were less abundant. The results were compared to two other major acute geriatric issues: infectious diseases and hip fracture. In acute phase, compared to healthy aged subjects, the abundance of 15/22 transcripts was also altered in both geriatric infectious diseases and hip fracture. Many variations had not vanished at the recovery phase. The abundance of CD28, CD69, LCK, HMOX1, TNFRSF1A transcripts, known to be altered in healthy aged versus healthy young subjects, was further affected in acute phase of the three geriatric diseases considered. The transcript levels of BCL2, CASP8, CCL5, [[DDIT3]], EGR3, IL10RB, IL1R2, SERPINB2 and TIMP1 were affected in all three pathological conditions compared to healthy aged, but not versus healthy young subjects. In conclusion, this work provides critical targets for therapeutic research on geriatric heart failure, infectious diseases and hip fracture.
MeSH Terms
- Adult
- Aged
- Aged, 80 and over
- Aging
- Biomarkers
- Communicable Diseases
- Female
- Heart Failure
- Hip Fractures
- Hospitalization
- Humans
- Male
- Neutrophils
- Transcription, Genetic
The abundance of a selection of transcript species involved in inflammation, immunosenescence and stress response was compared between PBMC of 35 geriatric patients with hip fracture in acute phase (days 2-4 after hospitalization) or convalescence phase (days 7-10) and 28 healthy aged controls. Twenty-nine differentially abundant transcripts were identified in acute phase versus healthy ageing. Twelve of these transcripts remained differentially abundant in convalescence phase, and 22 were similarly differentially abundant in acute phase of geriatric infectious diseases. Seven of these 22 transcripts were previously identified as differentially abundant in PBMC of healthy aged versus healthy young controls, with further alteration for CD28, CD69, LCK, CTSD, HMOX1, and TNFRSF1A in acute phase after geriatric hip fracture and infectious diseases. The next question is whether these alterations are common to other geriatric diseases and/or preexist before the clinical onset of the diseases.
MeSH Terms
- Acute-Phase Reaction
- Adult
- Aged
- Aged, 80 and over
- Aging
- Antigens, CD
- Antigens, Differentiation, T-Lymphocyte
- Base Sequence
- CD28 Antigens
- Case-Control Studies
- Cathepsin D
- DNA Primers
- Female
- Gene Expression Profiling
- Heme Oxygenase-1
- Hip Fractures
- Hospitalization
- Humans
- Lectins, C-Type
- Leukocytes, Mononuclear
- Lymphocyte Specific Protein Tyrosine Kinase p56(lck)
- Male
- Receptors, Tumor Necrosis Factor, Type I
Declines in immune function have been associated with declines in the function of naïve CD4 T cells. In vitro studies of naïve CD4 T cells in TCR-specific transgenic AND mice have shown age-related defects in immunosynapse formation, activation, proliferation and cytokine production. Previous work has also documented age-related alteration in the glycosylation of surface proteins involved in TCR signaling, and shown that enzymatic treatments to remove specific surface glycoproteins can restore in vitro function in CD4 cells from aged mice. Here an adoptive transfer system shows that a large percentage of naïve CD4 T cells from old mice fail to express CD69 and expand in antigen-primed mice, but these declines in CD69 and expansion can be restored by ex vivo pretreatment of the T cells with the bacterial enzyme O-sialoglycoprotein endopeptidase (OSGE). OSGE treatment also repairs the age-dependent loss of CD69 expression after in vivo activation.
MeSH Terms
- Aging
- Animals
- Antigens
- Antigens, CD
- Antigens, Differentiation, T-Lymphocyte
- CD4-Positive T-Lymphocytes
- Cell Proliferation
- Cells, Cultured
- Glycosylation
- Immune Tolerance
- Lectins, C-Type
- Lymphocyte Activation
- Metalloendopeptidases
- Mice
- Mice, Transgenic
- Receptors, Antigen, T-Cell
The immune system declines with age leading to a progressive deterioration in the ability to respond to infection and vaccination. Age-associated thymic involution is one of the most recognized changes in the ageing immune system and is believed to be a major contributor towards immunosenescence; however, the precise mechanisms involved in age-associated thymic involution remain unclear. In order to gain further insight into the effect of ageing on T-cell development, steady-state thymopoiesis was studied in mice ranging from 1 to 18 months of age. There was a decrease in thymic cellularity with age, but the most dramatic loss occurred early in life. Although there were no alterations in the proportion of the major thymocyte subsets, there was a significant decline in the expression of other key molecules including CD3 and CD24. There was a decline in the ability of thymocytes from older mice to respond to mitogens, which was demonstrated by a failure to up-regulate expression of the activation marker CD69 and to enter the G(2)--M phase of the cell cycle. This was concurrent with an increased resistance to apoptosis in thymocytes from aged animals. Together, these results suggest that T cells may be flawed even before exiting to the periphery and that this could contribute to the age-associated decline in immune function.
MeSH Terms
- Age Factors
- Aging
- Analysis of Variance
- Animals
- Antigens, CD
- Apoptosis
- Cell Count
- Cell Cycle
- Cell Differentiation
- Cell Proliferation
- Flow Cytometry
- Mice
- Phenotype
- T-Lymphocytes
- Thymus Gland
Age-related changes of gene expression contribute to the physiological alteration observed with human ageing. Herein, the abundance of a selection of 148 transcripts involved in immunosenescence and stress response was compared in total RNA of PBMC of healthy young to middle-age probands (35.0 /- 6.5 year old) and healthy old probands (82.5 /- 6.8 year old). This study provides a list of 16 differentially abundant transcripts species in the healthy old probands. Thus, these changes of abundance can be considered as easily accessible biomarkers of ageing. Some of these differential abundances like CD28, CD69, LCK (decreased abundance in old subjects), CD86, Cathepsin D, H and S (increased abundance in old subjects) might explain biochemical and cytochemical changes observed at the protein level in the immune system and thus might correspond to regulatory processes affecting the ageing process. Indeed these changes reflect the low-grade pro-inflammatory status observed in old persons and suggest a hypo-responsiveness of T-cells together with an increase in antigen presentation potential. In addition, among the differentially abundant transcripts were transcripts involved in the oxidative stress response HMOX1 and HSPA6 mRNAs were found as more abundant in PBMC from elderly subjects.
MeSH Terms
- Adult
- Aged
- Aged, 80 and over
- Aging
- Antigen Presentation
- Biomarkers
- Gene Expression Profiling
- Humans
- Leukocytes, Mononuclear
- Oligonucleotide Array Sequence Analysis
- Oxidative Stress
- RNA, Messenger
The purpose of this study was to investigate the modulation of selected cell surface markers and proinflammatory cytokines production in relation to ageing, and cigarette smoking. The analysis of cell surface receptors was performed by the flow cytometry and cytokines levels were evaluated by the sandwich enzyme immunoassays. We found a decreased expression of CD69, CD28, CD11b, CD95 markers in old population compared to young people (p<0.05; p<0.001). The memory CD45RO lymphocytes were markedly expanded in older population in comparison to young donors (12.93 /-5.92 %, p<0.001) and the selectin CD62L was significantly increased on granulocytes in aged people (p<0.05). Our findings demonstrated an augmented level of CD3 and CD28 on lymphocytes in smokers (p<0.05; p<0.005). The significant depression of CD16 56 molecule was recorded in smokers (10.86 /-0.80%) when compared to non-smokers (14.44 /-0.46; p<0.05). Our results showed a significantly diminished levels of interleukin (IL)-1beta (1.93 /-0.48 pg/ml), and increased levels of IL-6 and tumor necrosis factor (TNF)-alpha in elderly population compared to young people (p<0.05; p<0.001). The present data support previous suggestions that senescence and cigarette smoking may contribute to changes in the immune system activity, resulting in altered cell surface marker expression and cytokine levels (Tab. 1, Fig. 3, Ref. 81). Full Text (Free, PDF) www.bmj.sk.
MeSH Terms
- Adult
- Aged
- Aging
- Antigens, CD
- Cytokines
- Humans
- Interleukin-1beta
- Interleukin-6
- Middle Aged
- Smoking
- Tumor Necrosis Factor-alpha
- Young Adult
Human CMV infection of the neonatal CNS results in long-term neurologic sequelae. To define the pathogenesis of fetal human CMV CNS infections, we investigated mechanisms of virus clearance from the CNS of neonatal BALB/c mice infected with murine CMV (MCMV). Virus titers peaked in the CNS between postnatal days 10-14 and infectious virus was undetectable by postnatal day 21. Congruent with virus clearance was the recruitment of CD8( ) T cells into the CNS. Depletion of CD8( ) T cells resulted in death by postnatal day 15 in MCMV-infected animals and increased viral loads in the liver, spleen, and the CNS, suggesting an important role for these cells in the control of MCMV replication in the newborn brain. Examination of brain mononuclear cells revealed that CD8( ) T cell infiltrates expressed high levels of CD69, CD44, and CD49d. IE1(168)-specific CD8( ) T cells accumulated in the CNS and produced IFN-gamma and TNF-alpha but not IL-2 following peptide stimulation. Moreover, adoptive transfer of brain mononuclear cells resulted in decreased virus burden in immunodepleted MCMV-infected syngeneic mice. Depletion of the CD8( ) cell population following transfer eliminated control of virus replication. In summary, these results show that functionally mature virus-specific CD8( ) T cells are recruited to the CNS in mice infected with MCMV as neonates.
MeSH Terms
- Aging
- Animals
- Animals, Newborn
- Brain
- CD8-Positive T-Lymphocytes
- Cell Movement
- Cell Separation
- Cells, Cultured
- Central Nervous System Diseases
- Female
- Herpesviridae Infections
- Immediate-Early Proteins
- Interferon-gamma
- Liver
- Male
- Mice
- Mice, Inbred BALB C
- Monocytes
- Muromegalovirus
- Phenotype
- Survival Rate
- Virus Replication
Glucocorticoids (GCs) are primarily synthesized in the adrenal glands but an ectopic production has also been reported in the brain, the gastrointestinal tract and in thymic epithelial cells (TEC). Here we show that thymocytes express genes encoding for all enzymes required for de novo GC synthesis and produce the hormone as demonstrated by both a GC specific reporter assay and a corticosterone specific ELISA assay. Interestingly, GC synthesis is detectable in cells from young mice (4 weeks) and thereafter increases during aging (14-22 weeks) together with an increased gene expression of the rate-limiting enzymes StAR and CYP11A1. Hormone production occurred at a thymocyte differentiation stage characterized by being double positive for the CD4 and CD8 surface markers but was found to be unrelated to CD69 expression, a marker for thymocytes undergoing positive selection. No GC synthesis was found in resting or anti-CD3 activated CD4 and CD8 positive T cells isolated from the spleen. Thymocyte-derived GC had an anti-proliferative effect on a GR-transfected cell line and induced apoptosis in thymocytes. The age- and differentiation stage-related GC synthesis in thymocytes may play a role in the involution process that the thymus gland undergoes.
MeSH Terms
- Aging
- Animals
- Antigens, CD
- Biomarkers
- Cell Proliferation
- Cells, Cultured
- Coculture Techniques
- Gene Expression Profiling
- Genes, Reporter
- Glucocorticoids
- Humans
- Male
- Mice
- Mice, Inbred C57BL
- Spleen
- Thymus Gland
Aging is associated with a decline in immune responses, particularly within the T cell compartment. While the expansion of specific T cells in response to virus infections is consistently decreased in aged mice, the differences in T cell activation between young and aged mice as demonstrated in each round of proliferation remain poorly defined. In the present study, we utilized the T cell mitogen, ConA, to explore if fewer T cells of aged mice initiate proliferation upon mitogen stimulation or if similar numbers of T cells of aged mice begin proliferation but undergo fewer rounds of division. We also examined whether these age-associated changes in proliferation are reflected by differences in T cell activation by comparing activation markers (CD25, CD69, CD44, and CD62L) on T cells of young and aged mice at each round of proliferation. Not only was the kinetics of the expression of these markers greatly different between young and aged mice on the entire CD8 T cell population, but also at each round of proliferation. Our results demonstrate that a larger percentage of CD8 T cells of aged mice do not proliferate at all upon stimulation. Of the CD8 T cells of aged mice that do proliferate, a larger percentage start later and stop sooner. These results suggest that multiple levels of alteration may need to be considered when trying to maximize the immune response of aged individuals.
MeSH Terms
- Aging
- Animals
- Cell Proliferation
- Cells, Cultured
- Cellular Senescence
- Concanavalin A
- Lymphocyte Activation
- Male
- Mice
- Mice, Inbred C57BL
- Mitogens
- T-Lymphocytes
Ageing of the endocrine system (endocrinosenescence) has been closely related to immunosenescence. Dehydroepiandrosterone sulphate (DHEAS), a steroid hormone produced by the adrenals with reported enhancing immunomodulatory properties, consistently decline during ageing in parallel to detrimental increase in peripheral glucocorticoids. We investigated here the adjuvant effects of DHEAS during intraperitoneal immunization to Mycobacterium tuberculosis heat shock protein 70 (mycHSP70) in old (24 months) as well as young (3 months) BALB/c mice. Both young and old mice had significantly higher Immunoglobulin G (IgG) levels following immunization. Young mice co-immunized with mycHSP70-DHEAS presented an early increase in specific IgG levels and showed increased Interferon-gamma production compared to old mice. Also, T cells of immunized young animals were consistently more resistant to the immunosuppressive effects of glucocorticoids and to DHEAS. DHEAS was not effective in modulating antigen-specific T-cell proliferation, Interleukin-2 production or percentage of recent activated T-cell subsets (CD4 CD69 and CD8 CD69 ). Our data further indicate mycHSP70 as a putative good antigen in vaccine to tuberculosis. Our data also suggest that DHEAS produced adjuvant effects upon humoral and some cellular immune responses of young, but not old mice and indicate that immunization with DHEAS is capable of changing T-cell responses to steroids.
MeSH Terms
- Adjuvants, Immunologic
- Aging
- Animals
- Antibody Formation
- Antigens, CD
- Bacterial Proteins
- Cells, Cultured
- Corticosterone
- Dehydroepiandrosterone Sulfate
- Dexamethasone
- Dose-Response Relationship, Drug
- Female
- HSP70 Heat-Shock Proteins
- Immunity, Cellular
- Immunoglobulin G
- Interferon-gamma
- Interleukin-2
- Lymphocyte Activation
- Mice
- Mice, Inbred BALB C
- T-Lymphocytes
- Time Factors
- Tuberculosis Vaccines
- Vaccination
Previous work from our laboratory has shown that modifying cell surface glycosylation with either a Clostridium perfringens-derived sialidase (CP-Siase), or an O-linked glycoprotein endopeptidase (OSGE) can enhance the function of CD4 T cells from both young and old mice at multiple levels. Here we have re-assessed the effect of age on CD8 T-cell function, and examined the outcome of enzymatic treatment with CP-Siase and OSGE on its different aspects. Pre-treatment of CD8 T cells with either CP-Siase or OSGE led to a significant increase in anti-CD3-mediated Ca2 response in both young and old mice. Pre-treated CD8 T cells from both age groups also displayed a significant increase in activation-induced CD69 and CD25 expression, and produced significantly higher amounts of interleukin-2 and interferon-gamma in comparison to their untreated counterparts. Furthermore, pretreatment with either enzyme enhanced granzyme B expression in CD8 T cells, and increased their cytolytic activity in vitro. These data support the notion that glycosylated surface proteins hinder CD8 T-cell activation and function in both young and old mice, and raise the possibility of significantly improving CD8 T cell function in older individuals through enzymatic alteration of surface glycoproteins.
MeSH Terms
- Aging
- Animals
- Antigens, CD
- Antigens, Differentiation, T-Lymphocyte
- CD28 Antigens
- CD3 Complex
- CD8-Positive T-Lymphocytes
- Calcium
- Cells, Cultured
- Cytotoxicity, Immunologic
- Glycosylation
- Granzymes
- Interferon-gamma
- Interleukin-2
- Lectins, C-Type
- Lymphocyte Activation
- Male
- Membrane Glycoproteins
- Metalloendopeptidases
- Mice
- Mice, Inbred BALB C
- Mice, Inbred C57BL
- Neuraminidase
- Receptors, Interleukin-2
- Serine Endopeptidases
- Signal Transduction
Although human T cells enter the peripheral lymphoid tissues early during fetal development, the adaptive immune system in the fetus has largely been regarded as functionally immature and unresponsive to stimulation. In this study, we show that depletion of fetal CD4 CD25(high) T regulatory (T(Reg)) cells, which are present at high frequency in fetal lymphoid tissues, results in vigorous T cell proliferation and cytokine production in vitro, even in the absence of exogenous stimulation. Analysis of CD4 and CD8( ) T cell populations revealed a large subset of cells that expressed the early activation Ag, CD69. We show that this population represents a subset of highly reactive fetal T cells actively suppressed by fetal CD4 CD25(high) T(Reg) cells during development. These findings indicate that fetal T cells are, in the absence of CD4 CD25(high) T(Reg) cells, highly responsive to stimulation and provide evidence for an important role for CD4 CD25(high) T(Reg) cells in controlling T cell responses in utero.
MeSH Terms
- Adult
- Aging
- Cells, Cultured
- Female
- Fetal Development
- Humans
- Immune Tolerance
- Lymph Nodes
- Lymphocyte Count
- Lymphoid Tissue
- Pregnancy
- T-Lymphocytes, Regulatory
There are a few reports that chronic fatigue syndrome (CFS) may be accompanied by changes in hormones, such as dehydroepiandrosterone (DHEA) and insulin-like growth factor (IGF1). This study examines the serum concentrations of DHEA-sulfate (DHEAS), IGF1 and IGF1 binding protein-3 (IGFBP3) in 20 patients with CFS and in 12 normal controls. The IGFBP3/IGF1 ratio was computed as an index for IGF1 availability. We found significantly lower serum DHEAS concentrations in CFS, but no significant differences either in IGF1 or the IGFBP3/IGF1 ratio between CFS patients and normal controls. The decrease in serum DHEAS was highly sensitive and specific for CFS. There were significant and positive correlations between serum DHEAS and serum zinc and the mitogen-induced expression of the CD69 molecule on CD3 CD8 T cells (an indicator of early T cell activation). There was a significant and negative correlation between serum DHEAS and the increase in the serum alpha-2 protein fraction (an inflammatory marker). Serum IGF1, but not DHEAS, was significantly and inversely correlated to age. The results show that CFS is accompanied by lowered levels of DHEAS and that the latter may play a role in the immune (defect in the early activation of T cells) and the inflammatory pathophysiology of CFS.
MeSH Terms
- Aging
- Antigens, CD
- Antigens, Differentiation, T-Lymphocyte
- Biomarkers
- CD3 Complex
- CD8-Positive T-Lymphocytes
- Dehydroepiandrosterone Sulfate
- Fatigue Syndrome, Chronic
- Female
- Humans
- Inflammation
- Insulin-Like Growth Factor Binding Protein 3
- Insulin-Like Growth Factor I
- Lectins, C-Type
- Lymphocyte Activation
- Lymphocyte Count
- Male
- Zinc
Type I IFN (IFN-I or IFN-alphabeta) plays an important role in the innate immune response against viral infection. Here we report that a potent inducer of IFN-alphabeta, polyinosinic-polycytidylic acid [poly(I:C)], led to the depletion of T cells in young, but not aged mice, and that this depletion was limited to central memory, but not effector memory, T cells. Although early activation of T cells in vivo by poly(I:C), as demonstrated by CD69, was not impaired with aging, the expression of active caspase-3 was higher in young compared with aged mice. This depletion of T cells and induction of active caspase-3 in young mice and of CD69 in both young and aged mice by poly(I:C) were blocked by anti-IFN-alphabeta Ab. Although poly(I:C) stimulated lower circulating levels of IFN-alphabeta in aged mice, administration of IFN-alphabeta after poly(I:C) did not induce depletion of T cells in aged mice. These results indicate that IFN-alphabeta plays a critical role in the depletion of T cells of young mice, and further suggest that the lower level of functional IFN-alphabeta and decreased induction of active caspase-3 in T cells of aged mice after poly(I:C) may be responsible for the increased resistance of T cells of aged mice to depletion.
MeSH Terms
- Aging
- Animals
- Apoptosis
- CD4-Positive T-Lymphocytes
- CD8-Positive T-Lymphocytes
- Immunologic Memory
- Immunophenotyping
- Injections, Intravenous
- Interferon Inducers
- Interferon Type I
- Lymphocyte Activation
- Lymphopenia
- Male
- Membrane Proteins
- Mice
- Mice, Inbred C57BL
- Poly I-C
- Receptor, Interferon alpha-beta
- Receptors, Interferon
HIV-1 infection alters expression of CCR5 and CXCR4 on CD4 T cells in adults, although an effect by virus on expression of coreceptor genes in pediatric subjects is unknown. We designed an exploratory study to evaluate surface expression of CXCR4 and CCR5 on CD45RA and CD45RO subsets of CD4 T lymphocytes from 17 HIV-1-infected infants and adolescents and 16 healthy age-matched individuals. While age in the absence of HIV-1 infection was unrelated to coreceptor expression, infection affected coreceptor expression differentially in infants and adolescents. Among infected adolescents, CCR5 and CXCR4 expression was significantly increased on CD4 CD45RO T cells, while CXCR4 was diminished in the CD4 CD45RA subset. Although HIV-1 infection in infants was also associated with increased CXCR4 expression on the CD4 CD45RO subset, in contrast to adolescents, infection in infants had no impact on coreceptor expression within the CD45RA CD4 subset. The proportion of CD4 T cells coexpressing CD45RA and CD45RO was increased by infection in both infants and adolescents. The CD45RA CD45RO subset in culture expressed high levels of CD4, CXCR4, and CD69, an early activation marker, and was highly susceptible to HIV-1 infection and replication. Infection of transitional CD4 T cells coexpressing CD45RA and CD45RO could contribute in part to provirus in either CD45RA or CD45RO subsets. Deleterious effects by HIV-1 infection on CD4 T cell homeostasis were greater in infants then adolescents, indicating that adolescence may be an optimal age group for assessing vaccines to prevent or treat HIV-1 infection.
MeSH Terms
- Adolescent
- Adult
- Aging
- CD4-Positive T-Lymphocytes
- Cells, Cultured
- Child
- Child, Preschool
- Female
- HIV Infections
- HIV-1
- Humans
- Infant
- Leukocyte Common Antigens
- Male
- Protein Tyrosine Phosphatase, Non-Receptor Type 1
- Receptors, CCR5
- Receptors, CXCR4
- T-Lymphocyte Subsets
Decreased proliferation of CD4( ) lymphocytes of elderly people is at least in part due to lowered proportion of cells that are capable of dividing and producing viable progeny (effective precursors). We show that age-dependent reduction in effective precursor numbers depends on the one hand, extensive, activation-dependent apoptosis occurring from the very onset of stimulation and, on the other, the accumulation of non-dividing, regulatory (suppressor) CD4(lo)CD25( )CD28(lo) T cells. In addition, analysis of changes in surface expression of activation-related antigens, including CD25, CD69, and PCNA in consecutive generations of dividing CD4( ) cells traced by carboxyfluorescein diacetate succinimidyl ester staining showed variable patterns of these changes that may relate to various aspect of impaired division of these cells in elderly.
MeSH Terms
- Adult
- Aged
- Aging
- Antigens, CD
- Apoptosis
- CD4-Positive T-Lymphocytes
- Cell Division
- Cells, Cultured
- Cellular Senescence
- Humans
- Lymphocyte Activation
- Middle Aged
- Proliferating Cell Nuclear Antigen
- T-Lymphocyte Subsets
CD4( ) T cells from old mice show defects in the activation process including deficiency in the formation of immunosynapses with antigen-presenting cells. We show that CD4( ) T cells from old mice express unusually high levels of glycosylated forms of the bulky T cell glycoprotein CD43, particularly on a subset of functionally anergic cells expressing P-glycoprotein. T cells from old donors also show a decline in the association of CD43 with cytoskeletal matrix and in the proportion of T cells that can exclude CD43 from the synapse. O-sialoglycoprotein endopeptidase, which removes the external domain of CD43 and other O-sialoglycoproteins from the aged naive CD4( ) T cells of TCR-transgenic mice, restores early agonist-independent stages and later agonist-dependent stages of synapse formation as well as expression of the activation markers CD69 and CD25 to the levels found in the young mice. These data support a model in which O-glycosylated forms of T cell surface molecules, including CD43, are largely responsible for age-related defects in TCR signaling and function.
MeSH Terms
- Aging
- Animals
- Antigens, CD
- Antigens, Differentiation, T-Lymphocyte
- CD4-Positive T-Lymphocytes
- Cells, Cultured
- Cytoskeleton
- Glycosylation
- Lectins, C-Type
- Leukosialin
- Lymphocyte Activation
- Metalloendopeptidases
- Mice
- Protein Isoforms
- Protein Transport
- Receptors, Interleukin-2
- Sialoglycoproteins
- Synapses
The age-related decline of immunological functions is well established but it remains largely unknown which specific changes are related to disease. We analyzed peripheral blood lymphocytes of 42 healthy elderly as well as 24 healthy young subjects from southern Brazil. No differences in phytohemagglutinin-induced proliferation and CD4:CD8 ratio were found between the subjects. However, CD4 expression (considering mean fluorescence intensity) was found upregulated in elderly subjects. No changes in activation molecules CD25, CD28, CD69 and CD95 were observed. A reduced proportion of naive (CD45RA ) T cells was found in the elderly compared to young subjects. No changes in adhesion molecule expression (CD11c and CD31) were observed. However, the frequencies of CD49d-positive cells, as well as expression of CD62L, were increased in the eldery subjects. We further described two subgroups of eldery subjects with an immunological risk profile defined by lower CD4:CD8 ratio and reduced proliferative response to mitogens. These data suggest that healthy aging is associated with intact T-cell proliferation and some compensatory immunophenotypical changes.
MeSH Terms
- Adult
- Aged
- Aging
- Antigens, CD
- Brazil
- Female
- Humans
- Immunophenotyping
- Male
- Middle Aged
- T-Lymphocyte Subsets
- T-Lymphocytes
The ontogeny of the human immune system was studied by analyzing fetal and adult tissues for the presence of various lymphocyte populations and activation/maturation markers. CD95 (fas) was expressed in hematopoietic tissues during the final stages of development of monocytes, granulocytes, NK cells and T cells, but to a much lesser extent on B cells. In the periphery, CD95 expression declined on granulocytes and NK cells. CD95 was expressed at a higher level on CD45RA peripheral T-cells in the fetus than in the adult. Contrary to the belief that most fetal T-cells are naïve or resting, a notable number of CD45RO T-cells were observed as well as an unique CD95-CD45RO population. Activation markers CD25, CD122, CD69 and CD80 were also present on fetal T-cells. These findings indicate that in the initial weeks following thymic maturation, a high frequency of T-cells is activated in the periphery of the fetus.
MeSH Terms
- Adult
- Aging
- Biomarkers
- Fetus
- Flow Cytometry
- Humans
- Immunophenotyping
- Leukocyte Common Antigens
- Lymphocyte Activation
- Protein Isoforms
- Receptors, Antigen, T-Cell, alpha-beta
- Receptors, Cytokine
- T-Lymphocytes
- fas Receptor
gammadelta T lymphocytes are considered to represent a link between the inflammatory response and adaptive immunity. In the present paper we investigated whether these cells play any role in the remodeling of the immune system described in the elderly. We show that the absolute number of gammadelta T cells in peripheral blood of old and very old subjects is reduced. Moreover, gammadelta T cells from old people and centenarians show enhanced levels of the early activation marker CD69 both after culture in medium alone and in LPS-stimulated cells. Furthermore, they show a basal increased production of tumor necrosis factor (TNF)-alpha as evaluated at the single cell level. Additionally, the response of these cells to IPP in "in vitro" cultures is in part impaired. These results suggest that the high level of basal activation of gammadelta T cells is due to the "inflamed" environment. However, the changes in number and function of gammadelta T lymphocytes might influence the resolution of inflammatory immune responses in the elderly.
MeSH Terms
- Adult
- Aged
- Aged, 80 and over
- Aging
- Cells, Cultured
- Female
- Humans
- Lipopolysaccharides
- Lymphocyte Activation
- Lymphocyte Count
- Male
- Middle Aged
- Receptors, Antigen, T-Cell, gamma-delta
- T-Lymphocytes
- Tumor Necrosis Factor-alpha
The relevance of physiological immune aging is of great interest with respect to determining disorders with pathologic immune function in aging individuals. In recent years, the relevance of changes in peripheral lymphocytes in age-associated neurologic diseases has become more evident. Due to the lack of immunological studies, covering more than one event after mitogenic activation, we envisaged a new concept in the present study, aiming to investigate several events, starting from T cell receptor (TCR) ligation up to T cell proliferation. In addition, we addressed the question whether changes are present in the subsets (CD4, CD8) with aging. Phosphorylation of tyrosine residues declines with increasing age in CD4( ) cells. Fewer levels of CD69 positive cells after 4 h mitogenic activation, altered expression of cytokines (IL2, IFN-gamma and TNF-alpha; 22 h) and lower proliferation (72 h) were determined in aging. Moreover, it could be shown that CD8( ) lymphocytes react more effectively to mitogenic stimulation with reference to CD69 expression and proliferation in both age groups (<35 and >60 years old). These data indicate that T cell activation, mediated by TCR engagement, is significantly impaired in aging and both subsets are affected. However, bypassing the TCR does not fully restore T cell function, indicating that there are more mechanisms involved than impaired signal transduction through TCR only. The results will be discussed in relation to their relevance in neurodegenerative and psychiatric disorders.
MeSH Terms
- Adult
- Aged
- Aging
- Antigens, CD
- Antigens, Differentiation, T-Lymphocyte
- CD4 Lymphocyte Count
- CD4-CD8 Ratio
- CD4-Positive T-Lymphocytes
- CD8-Positive T-Lymphocytes
- Cell Division
- Female
- Humans
- Interferon-gamma
- Interleukin-2
- Ionomycin
- Lectins, C-Type
- Lymphocyte Activation
- Lymphocyte Count
- Male
- Middle Aged
- Phosphorylation
- Phytohemagglutinins
- Receptors, Antigen, T-Cell
- Tetradecanoylphorbol Acetate
- Tumor Necrosis Factor-alpha
- Tyrosine
T cell function is altered in vivo and in vitro in elderly compared with young subjects, and this alteration is believed to contribute to morbidity and mortality in man due to the greater incidence of infection, as well as autoimmunity and cancer in elderly. The majority of T cells express TCRalphabeta whereas TCRgammadelta is expressed on a minority of T cells. Moreover, it is known that gammadelta T lymphocytes display major histocompatibility complex (MHC)- unrestricted cytotoxicity that is reminiscent of natural killer (NK) activity. In view of earlier findings on both T cells and NK cells in the elderly, we hypothesised a different behaviour of gammadelta T lymphocytes from old subjects when compared with gammadelta T lymphocytes obtained from young people. Therefore, to gain further insight into mechanisms of immunosenescence in this little-studied population, we studied immunofluorescence analysis gammadelta T cells from the elderly. Our preliminary results show that the percentage of blood gammadelta T cells in lymphocytes from old subjects is decreased when compared with the young. Interestingly, these cells are more activated in the elderly than in young subjects; expression of CD69, an early activation marker, is increased in gammadelta T lymphocytes from old subjects after three hours of in vitro culture both with and without lipopolysaccharide stimulation. Thus, our findings, which need confirmation, strongly suggest that, in humans, gammadelta T cells are early responders when compared with alphabeta T cells. They may act as 'first aid' cells to replace the described deficit of the specific and aspecific immunity in elderly. In this view, the proinflammatory status, observable in the elderly, renders them ready to be stimulated by exogenous agents.
MeSH Terms
- Adult
- Aged
- Aged, 80 and over
- Aging
- Antigens, CD
- Antigens, Differentiation, T-Lymphocyte
- Female
- Humans
- Lectins, C-Type
- Male
- Middle Aged
- Receptors, Antigen, T-Cell, gamma-delta
- T-Lymphocytes
We analysed the properties of intraepithelial lymphocytes of small intestine (SI-IEL) in KN6-transgenic (Tg) mice expressing cDNA of T-cell receptor (TCR)-gammadelta specific for the T22b molecule. While most splenic Tg TCR-gammadelta cells from KN6-Tg mice with H-2d/d background (Tgd/d mice) were Thy-1 CD8alpha- CD44dull CD45RB CD69-, Tg TCR-gammadelta cells in SI-IEL (Tg gammadelta-IEL) were heterogeneous in the expression of Thy-1, CD8alpha and CD44 molecules and predominantly CD45RB CD69 . Tg gammadelta-IEL exhibited a much reduced proliferative response to the antigen (irradiated H-2b splenocytes) than splenic Tg TCR-gammadelta cells; the CD44 subset, but not the CD44- subset, in Tg gammadelta-IEL responded to the antigen. Furthermore, Tg gammadelta-IEL, but not splenic Tg TCR-gammadelta cells, displayed cytolytic activity whether they were prepared from conventional or germ-free KN6-Tg mice. Comparative analysis of young and aged KN6-Tg mice revealed that the proportion of CD44 cells in Tg gammadelta-IEL increased but the proliferative response of Tg gammadelta-IEL to the antigen attenuated in association with ageing. Moreover, although Tg gammadelta-IEL from Tgb/d mice contained a higher proportion of CD44 cells than Tgd/d mice, they did not respond to the antigen. These results demonstrate that Tg TCR-gammadelta cells lose the ability to recognize the antigen following activation in the intestinal epithelia.
MeSH Terms
- Aging
- Animals
- Cell Division
- Epithelial Cells
- H-2 Antigens
- Immunity, Mucosal
- Intestinal Mucosa
- Intestine, Small
- Lymphocyte Activation
- Mice
- Mice, Inbred BALB C
- Mice, Inbred C57BL
- Mice, Transgenic
- Receptors, Antigen, T-Cell, gamma-delta
- Spleen
- T-Lymphocyte Subsets
A deficiency of neonatal T lymphocytes to express CD154 antigen in response to ionomycin and phorbol 12-myrsistate 13-acetate (PMA) stimulation or after CD3 cross-linking has been described. In the present report we describe that CD45RA newborn cells are able to synthesize and express CD154 at similar or even higher levels than adult cells in response to ionomycin and cAMP-elevating agents which trigger the protein kinase A (PKA) -mediated metabolic pathway. Peak CD154 protein concentrations in newborn cells were found between 4 and 8 hr after stimulation with ionomycin and dibutyryl cAMP. These agents, however, did not induce expression of the early activation antigen CD69. Surface levels of CD154 did not correlate with specific mRNA concentration, indicating that dibutyryl cAMP up-regulates CD154 by acting at a post-transcriptional stage. The CD154 antigen induced by PKA activation of newborn cells was functional, since upon binding to CD40 on B lymphocytes in the presence of interleukin-4 (IL-4), it promoted immunoglobulin heavy-class switching to IgE. We also found a different pattern of cytokine production between neonatal and adult CD4 T cells. In response to ionomycin and dibutyryl cAMP, cord blood cells were more prone than adult lymphocytes to secrete the T helper type 2-derived immunosuppressive cytokines IL-4 and IL-10. Taking into account that the feto-maternal environment is rich in cAMP-elevating agents, the reduced risk of graft versus host disease associated with cord blood trasplantation, as compared with the risk with adult bone marrow cell transplants, may be due to the bias of neonatal cells to differentiate towards the T helper type 2 functional cell subset.
MeSH Terms
- Adult
- Aging
- Bucladesine
- CD4-Positive T-Lymphocytes
- CD40 Antigens
- CD40 Ligand
- Cell Culture Techniques
- Cyclic AMP
- Cyclic AMP-Dependent Protein Kinases
- Cytokines
- Fetal Blood
- Humans
- Immunophenotyping
- Infant, Newborn
- Ionomycin
- Ligands
- Membrane Glycoproteins
In young mice, memory CD4 T lymphocytes with high P-glycoprotein activity (P-gp(high)) are unresponsive to TCR stimulation in vitro but can be activated by PMA plus ionomycin. The proportion of these hyporesponsive cells increases considerably with age. The earliest events in T cell activation were studied in P-gp(high) and P-gp(low) CD4 memory cells at the single-cell level using confocal immunofluorescence methods. Recruitment of both linker for activation of T cells (LAT) and protein kinase C-theta to the immunological synapse, i.e., the site of T cell interaction with stimulator cells, was greatly impaired in P-gp(high) cells from both young and old mice. Translocation of NF-AT to the nucleus, CD69 expression, and proliferative capacity were also diminished to a similar extent in P-gp(high) cells under the same activation conditions. In contrast, movement of c-Cbl to the synapse region occurred in a high proportion of CD4 memory T cells regardless of P-gp subset or age. Moreover, although P-gp(low) cells frequently recruited both c-Cbl and LAT to the APC synapse, cells in the less responsive P-gp(high) subset frequently relocated c-Cbl, but not LAT, to the interface region. In some systems, c-Cbl can act as a negative regulator of receptor-dependent tyrosine kinases, and alterations of c-Cbl to LAT ratios in the P-gp(high) subset may thus contribute to the hyporesponsiveness of this age-dependent, anergic memory cell population.
MeSH Terms
- ATP Binding Cassette Transporter, Subfamily B, Member 1
- Adaptor Proteins, Signal Transducing
- Aging
- Animals
- Antigens, CD
- Antigens, Differentiation, T-Lymphocyte
- Biological Transport
- CD4-Positive T-Lymphocytes
- Carrier Proteins
- Cell Line
- Cell Nucleus
- Clonal Anergy
- DNA-Binding Proteins
- Immunologic Memory
- Isoenzymes
- Lectins, C-Type
- Male
- Membrane Proteins
- Mice
- Mice, Inbred C57BL
- Mice, Inbred CBA
- Models, Immunological
- NFATC Transcription Factors
- Nuclear Proteins
- Phosphoproteins
- Protein Kinase C
- Protein Kinase C-theta
- Proto-Oncogene Proteins
- Proto-Oncogene Proteins c-cbl
- T-Lymphocyte Subsets
- Transcription Factors
- Ubiquitin-Protein Ligases
Natural killer (NK) cells are cytotoxic cells that play a critical role in the innate immune response against infections and tumors. Recent studies on NK cell biology have demonstrated that besides their cytotoxic function, NK cells express cytokine and chemokine receptors and also that they secrete other immunoregulatory cytokines and chemokines, supporting their relevance in the regulation of the immune response by promoting downstream adaptive, Th1 mediated, responses against infections. Immunosenescence is the deterioration of the immune response associated with aging. It is characterized mainly by a defective T cell response, but includes changes in the number and function of other cells of the innate immune system. Age-associated alterations in the number and function of NK cells have been reported. There is a general consensus that a progressive increase in the percentage of NK cells with a mature phenotype occurs in elderly donors associated with an impairment of their cytotoxic capacity when considered on a "per cell" basis. The response of NK cells from elderly individuals to IL-2 or other cytokines is also decreased in terms of proliferation, expression of CD69 and killing of NK-resistant cell lines. Furthermore early IFN-gamma and chemokine production in response to IL-2 or IL-12 is also decreased. However aging does not significantly alter other NK cell functions such as TNF-alpha production or perforin induction in response to IL-2. The percentage of T cells that co-express NK cell markers is also increased in aging. These results indicate that the increase in the number of "classical" mature NK and NK/T cells in aging is associated with a defective functional capacity of NK cells. Low NK cell number or function in elderly individuals is associated with increased mortality risk and increased incidence of severe infections, supporting the role of NK cells in the defense against infections in the elderly.
MeSH Terms
- Aged
- Aging
- Cytokines
- Cytotoxicity, Immunologic
- Humans
- Infections
- Killer Cells, Natural
- Phenotype
- T-Lymphocytes
The exocytosis of intracellular vesicles is an important function of the plasma membrane, which is responsible for hormone secretion, cell surface expression of antigens, ion transporters and receptors, and intracellular and intercellular signalling. Human aging is associated with many physiological and cellular changes, many of which are due to alterations in plasma membrane functioning. Alterations in vesicle externalization with age could account for many of these changes. We investigated whether alterations in vesicle exocytosis occur with increasing age by flow-cytometric determination of CD11b and CD69 expression on the surface of human polymorphonuclear leucocytes (PMN) stimulated with phorbol myristate acetate (PMA), a tumour promoter which binds to and activates protein kinase C (PKC) directly, or with formyl-Met-Leu-Phe (fMLP), which activates PKC indirectly via interactions with a cell surface receptor and G-protein, and subsequent inositol phosphate hydrolysis. Following stimulation with PMA, a decrease in the proportion of PMN expressing CD69 at high levels was observed in elderly compared with young subjects (young, 55.3%; elderly, 43.9%; P=0.01). No aging-related differences in the proportion of PMN expressing CD11b (young, 73.7%; elderly, 68.4%; P=0.15), or in the number of molecules of CD69 or CD11b expressed per cell, were observed. Stimulation with fMLP or low PMA concentrations resulted in full CD11b expression but minimal CD69 expression in both young and elderly subjects. Cells which expressed CD69 had no CD11b expression, while those cells expressing CD11b had minimal CD69 expression. Thus the PMA-induced expression of CD11b and CD69 in human PMN represents two separate processes, only one of which is affected in aging. CD11b expression appears to require a lesser degree of PKC stimulation compared with that required for CD69 expression. The age-associated reduction in PMA-stimulated CD69 expression may occur either at or distal to PKC activation. Such a decrease may contribute to the age-associated impairments in PMN function that contribute, in turn, to immunosenescence.
MeSH Terms
- Adult
- Aged
- Aging
- Antigens, CD
- Antigens, Differentiation, T-Lymphocyte
- CD11 Antigens
- Cell Culture Techniques
- Dose-Response Relationship, Immunologic
- Exocytosis
- Female
- Humans
- Lectins, C-Type
- Male
- Middle Aged
- N-Formylmethionine Leucyl-Phenylalanine
- Neutrophil Activation
- Neutrophils
- Tetradecanoylphorbol Acetate
Immunosenescence is a process that affects all cell compartments of the immune system. Age-associated changes have been demonstrated not only on T lymphocytes but also in different aspects of the innate immunity including natural killer (NK) cells. A significant expansion in the percentage of NK cells showing a mature phenotype has been found in healthy elderly donors, and the NK-cytotoxic capacity of total peripheral blood lymphocytes is well preserved in these individuals. However, NK-cell killing of K562 is impaired when considered on a per-cell basis. Furthermore, NK cells from elderly people show a decreased proliferative response to interleukin 2 and a parallel impaired expression of the CD69 activation antigen. The response to interleukin 2 of NK cells from aged donors is also impaired in terms of their capacity to kill NK-resistant cell lines, but not when K562 killing, perforin synthesis, or tumor necrosis factor alpha production are considered. Therefore phenotypic and functional alterations can be shown in NK cells in healthy aging. These changes are compatible with the expansion of a mature NK subset.
MeSH Terms
- Aged
- Aging
- Biomarkers
- Cell Division
- Cytokines
- Cytotoxicity, Immunologic
- Humans
- Interleukin-2
- Killer Cells, Natural
- Phenotype
Changes in T lymphocyte subsets have been observed in various forms of pulmonary disease. However, bronchoalveolar lymphocyte subsets have not been well characterised for healthy individuals differing in age. A study was undertaken to investigate the bronchoalveolar lavage (BAL) and peripheral blood lymphocyte subsets in clinically normal volunteers of two different age groups (19-36 and 64-83 years). Bronchoalveolar lavage was performed on all individuals in both age groups and peripheral venous blood was drawn just prior to BAL. Bronchoalveolar cell profiles were characterised by morphological criteria, and cell surface antigen expression of lymphocytes was determined by flow cytometry. A significant increase in total BAL lymphocytes was observed for the oldest group compared with the youngest age group. Mean lymphocyte subset (CD4 /CD8 ) ratios were significantly increased in BAL fluid from the older group compared with the younger group (mean (SE) 7.6 (1.5) vs 1.9 (0.2); p<0.0001). The increase in the BAL CD4 /CD8 T cell ratio was mostly due to an increase in relative numbers of CD4 lymphocytes, and the BAL CD4/CD8 ratio was disproportionately increased compared with peripheral blood in the older group. Increased expression of HLA-DR and CD69 on CD4 T lymphocytes was observed in the oldest age group. Relative numbers of natural killer (NK) cells did not vary with age, and gammadelta T cells and CD5 B cells were present in very low numbers in both age groups. CD4 T cells accumulate in air spaces of the lower respiratory tract with age in healthy adults and express increased amounts of HLA-DR and CD69 on their surfaces, suggesting a relative degree of CD4 T lymphocyte activation for healthy older individuals who have normal lung function.
MeSH Terms
- Adult
- Aged
- Aged, 80 and over
- Aging
- Bronchoalveolar Lavage Fluid
- CD4-CD8 Ratio
- Flow Cytometry
- Humans
- Immunity, Cellular
- Lung
- Middle Aged
- Phenotype
- T-Lymphocyte Subsets
Immunosenescence is a process that primarily affects the T cell compartment of the immune system, although age-associated immunological alterations have also been demonstrated in the NK cell phenotype and function. A significant expansion in the number of NK cells is found in aging. The NK cytotoxic capacity of total peripheral blood lymphocytes is also well preserved, not only in healthy elderly people but also in centenarians. However, NK cell killing of K562 is impaired when considered in a per-cell basis, and this defect is associated with defective signal transduction after activation more than a diminished conjugate formation or killing capacity. We have studied the phenotype of NK cells in elderly donors fulfilling the Senieur criteria. We have also studied the capacity of these cells to be activated by IL2 when different NK cell functions, other than cytotoxicity, are considered. Our results confirm the increased percentage of NK cells in the elderly due to the expansion of the CD56dim subset that also show an altered pattern of activation markers, whereas no differences were found in the CD56bright subset. The response of NK cells to IL2 was found to be impaired when proliferation, expression of CD69, and Ca2 mobilization were considered, whereas TNF-alpha production was not significantly affected. These results suggest that human NK cells do not escape the aging process, although senescence have a differential effect on distinct NK cell biological functions, ranging from severe to negligible impairment, depending on the parameters considered.
MeSH Terms
- Adult
- Aged
- Aged, 80 and over
- Aging
- Biomarkers
- CD3 Complex
- CD56 Antigen
- Calcium
- Cell Division
- Cytotoxicity, Immunologic
- Humans
- In Vitro Techniques
- Interleukin-2
- Killer Cells, Natural
- Lymphocyte Activation
- Phenotype
- Signal Transduction
- Tumor Necrosis Factor-alpha
We recently showed that mature T lymphocytes derived from elderly humans were more susceptible to activation-induced cell death than similar cells from young individuals. Because this excessive apoptosis is unrelated to either the age-associated decrease in IL-2 production, a differential Bcl-2 expression or to a modification of the antioxidant pathway, we examined the possibility that the Fas receptor (FasR) is directly implicated in the generation of the unwarranted death signal. We investigated the expression and the function of FasR on T lymphocyte populations from healthy young and elderly individuals. We found that the frequency of FasR T cells increases as a function of age. The FasR expressed at the surface of freshly isolated T lymphocytes from elderly donors appear to be fully functional since their ligation by a cytocidal IgM anti-Fas mAb leads to a significant increase in DNA fragmentation in this cell population. Conversely, exposure of T cells derived from aged individuals to an antagonistic anti-FasR mAb partially prevents the age-related increase in apoptotic cell death. The population of FasR T lymphocytes is essentially constituted of previously activated CD45RO cells and also includes recently activated lymphocytes bearing the CD25 and CD69 activation markers. The accumulation of chronically and recently in vivo activated T-cells with age probably contributes to the amplification of the process of Fas-mediated cell death in T lymphocytes isolated from senescent organisms.
MeSH Terms
- Adult
- Aged
- Aged, 80 and over
- Aging
- Apoptosis
- Fas Ligand Protein
- Humans
- Lymphocyte Activation
- Membrane Glycoproteins
- T-Lymphocytes
- fas Receptor
This study characterizes the early steps of T lymphocyte activation in elderly subjects. The expression of CD69, the earliest inducible antigen which appears with T lymphocyte activation, was assessed in T cells cultured with medium, anti-CD3 or PMA. The proliferative responses of T cells stimulated through CD69 and CD3 pathways were also studied. Donors included 31 healthy elderly [age mean (SD) 80(8) years] and 33 healthy young [age 30(5) years] subjects. In elderly people, the expression of CD69 was lower in T cells cultured with medium [3.4% (1.65-5.9; 25-75 percentiles) vs. 10% (6-18), p < 0.0003] and anti-CD3 activated [28.1% (16.5-53.8) vs. 79.5% (73-89), p < 0.0002] T cells. With PMA at 10 ng/ml, CD69 expression was higher in both groups of T cells, though still lower in the aged [84.5% (70.9-94.9) vs. 99% (65.7-100), p = 0.051]. CD69 T cells expression was equal in both groups with 2 ng/ml of PMA, but the co-stimulatory responses to CD69 under these conditions and in the presence of anti-CD3 were lower in the aged (16914 vs. 28904 cpm, p < 0.02) and (6944 vs. 14370 cpm, p < 0.02) respectively. Aged T cells failed to express CD25 at the same levels of young T cells when stimulated with CD69. These results suggests an age-associated defect in the very early steps of T lymphocyte activation that might influence later stages of lymphocyte function. An alteration in the transmission of the activation signal from the cell surface to protein kinase C may play a primary role in this defect.
MeSH Terms
- Aged
- Aged, 80 and over
- Aging
- Antigens, CD
- Antigens, Differentiation, T-Lymphocyte
- Female
- Humans
- Immune Tolerance
- Lectins, C-Type
- Lymphocyte Activation
- Male
- Reference Values
- T-Lymphocytes
Ageing is associated with complex remodelling in the phenotypic and functional profiles of T lymphocytes. We investigated whether expression of CD28 antigen on T cells is conserved throughout adulthood and ageing in humans. For this purpose we analysed T cells obtained from peripheral blood of 102 healthy people of ages ranging from 20 to 105 years. We found an age-related increase of CD28- T cells in percentage and absolute number, predominantly among CD8 T cells. CD28- T cells from aged donors analysed by flow cytometry appeared as resting cells (not expressing CD25, CD38, CD69, CD71, DR), bearing markers of cytotoxic activity (CD 11b and CD 57) and with a phenotype compatible with 'memory' cells (up-regulated CD2 and CD11a; CD62L absent). At the functional level, freshly isolated purified CD28- CD8 T cells showed high anti-CD3 redirected cytotoxic activity against Fc-bearing P815 cells. The same activity tested on freshly isolated bulk T lymphocytes was significantly augmented with age. We found a positive correlation between age, number of CD8 CD28- T cells and anti-CD3 redirected cytotoxicity by freshly isolated T cells. These data suggest that an activation of unknown nature within the cytotoxic arm of the immune system occurs with age. We speculate that these cytotoxic T lymphocytes (CTL) in vivo may constitute armed effector cells for immediate killing of targets bearing peptides from pathogens of intracellular origin.
MeSH Terms
- Adult
- Aged
- Aged, 80 and over
- Aging
- CD28 Antigens
- CD3 Complex
- CD8-Positive T-Lymphocytes
- Cell Separation
- Cytotoxicity, Immunologic
- Flow Cytometry
- Humans
- Lymphocyte Count
- Middle Aged