The T cell in the ageing individual

Immunosenescence and inflammaging in the aged horse

The equine population in the United States and worldwide now includes a higher percentage of geriatric horses than ever previously recorded, and as methods to treat and manage elderly equids are developed and refined, this aging population will likely continue to expand. A better understanding of how horses age and the effect of age on immunity and disease susceptibility is needed to enable targeted preventative healthcare strategies for aged horses. This review article outlines the current state of knowledge regarding the effect of aging on immunity, vaccine responsiveness, and disease risk in the horse, highlighting similarities and differences to what is observed in aged humans. Horses show similar but milder age-related alterations in immune function to those reported in people. Decreases in lymphocyte proliferation and antibody production and diminished response to vaccination have all been documented in elderly horses, however, increased risk of infectious disease is not commonly reported. Aged horses also show evidence of a proinflammatory state (inflammaging) yet appear less susceptible to the chronic diseases of people for which inflammation is a risk factor. Information is currently lacking as to why the horse does not experience the same risk of age-related disease (e.g., cancer, heart disease, neurodegeneration) as people, although a lack of negative lifestyle habits, differences in diet, exercise, genetics and physiology may all contribute to improved health outcomes in the older horse.

Mycobacterium tuberculosis: Implications of Ageing on Infection and Maintaining Protection in the Elderly

Several reports have suggested that ageing negatively affects the human body resulting in the alteration of various parameters important for sufficient immune health. Although, the breakdown of innate and adaptive immunity has been hypothesized to increase an individual's susceptibility to infections including Mycobacteria tuberculosis (M. tb), little research has been done to bridge this gap and understand the pathophysiology underlying how ageing increases the pathogenesis of M. tb infection. Our objective was to study research from a plethora of resources to better understand the pathogenesis of ageing and its link to the human immune system. To achieve this goal, this article explores how ageing decreases the collective T-cell immune response, reduces glutathione (GSH) production, over activates the mammalian target of rapamycin (mTORC1) pathway, inhibits autophagy and mitophagy, and alters various protective genes/transcription factors. Specifically highlighting how each of these pathways cripple an individual's immune system and increases their susceptibility from M. tb infection. Furthermore, research summarized in this article gives rise to an additional mechanism of susceptibility to M. tb infection which includes a potential defect in antigen presenting by dendritic cells rather than the T-cells response. Inflammaging has also been shown to play a role in the ageing of the immune system and can also potentially be a driving factor for increased susceptibility to M. tb infection in the elderly. In addition, this article features possible preventative strategies that could decrease infections like M. tb in this population. These strategies would need to be further explored and range from immunomodulators, like Everolimus to antioxidant supplementation through GSH intake. We have also proposed the need to research these therapies in conjunction with the administration of the BCG vaccine, especially in endemic populations, to better understand the risk contracting M. tb infection as well as ways to prevent infection in the first place.

SOCIAL ENVIRONMENT IMPROVES THE CYTOKINE PROFILE AND LYMPHOPROLIFERATIVE RESPONSE IN CHRONOLOGICALLY OLD AND PREMATURELY AGING MICE

Among the age-associated changes in the immune system, the most evident is the decrease in proliferative responses of lymphocytes to mitogenic stimuli, which is accompanied by the loss of cytokine network homeostasis. Chronic low-grade inflammatory stress, termed as sterile inflammation, is also observed during aging. In chronologically and prematurely aging mice, cohabitation with adult animals for two months favored improvements in several immune functions. This study aimed to determine whether cohabitation could restore several cytokine networks, improve lymphoproliferative responses to mitogens, and diminish sterile inflammation. Chronologically old mice (76±4 weeks) and prematurely aging mice (33±4 weeks) (PAM and TH-HZ) were cohabited with adults (without premature aging) for two months. Subsequently, lymphoproliferation in both basal (unstimulated) conditions and in the presence of mitogenic stimuli lipopolysaccharide A (LPS) or concanavalin A (ConA) was analyzed in cultures of peritoneal leukocytes for 48h. Cytokine secretions (IL-1β, TNF-α, IL-6, IL-10, and IL-17) in these cultures were also evaluated. The results showed that cohabitation restored the levels of these cytokines in old and prematurely aging mice and improved the subsequent lymphoproliferative responses. In addition, this social strategy diminished sterile inflammation and decreased inflammatory stress in unstimulated conditions. Therefore, this strategy seems to be capable of restoring the relevant immune function of lymphocytes and reducing the inflammatory stress, which are the improvements required for an adequate immune response.

Tonsillectomy in Adults over 40 Years of Age Does Not Increase the Risk of Pneumonia: A Three-Year Longitudinal Follow-Up Study

To evaluate the effect of tonsillectomy on the subsequent risk of pneumonia in an adult population, a longitudinal follow-up case control study was conducted using a national health screening cohort dataset between 2003 and 2012. A total of 1005 tonsillectomy participants were 1:4 matched with 4020 control participants for age, sex, income, and region of residence. The number of pneumonia diagnoses were counted from the index date (ID) to the date after the first-year (post-ID 1y), second-year (post-ID 2y), and third-year (post-ID 3y) periods. Simple linear regression and multiple linear regression were conducted to calculate estimated values (EVs) and 95% confidence intervals for each post-ID pneumonia and compared between the two groups. Subgroup analyses were performed according to age, sex, and the number of pneumonia cases during the year prior to the ID (pre-ID 1y). In the simple linear regression model, post-ID pneumonia did not show a significant correlation with tonsillectomy (post-ID 1y: EV = 0.003; post-ID 2y: EV = 0.007; post-ID 3y: EV = 0.013; all p > 0.05). In the multiple regression model, post-ID pneumonia also did not show a significant correlation with tonsillectomy (post-ID 1y: EV = 0.001; post-ID 2y: EV = 0.006; post-ID 3y: EV = 0.011; all p > 0.05). In the subgroup analyses, tonsillectomy did not show a significant correlation with post-ID pneumonia in either the simple linear regression or multiple linear regression models (all p > 0.05). Tonsillectomy performed in the adult population did not show any effect in increasing the incidence of pneumonia during the first three postoperative years.

Allo-priming as a universal anti-viral vaccine: protecting elderly from current COVID-19 and any future unknown viral outbreak

BACKGROUND

We present the rationale for a novel allo-priming approach to serve the elderly as a universal anti-virus vaccine, as well serving to remodel the aging immune system in order to reverse immunosenescence and inflammaging. This approach has the potential to protect the most vulnerable from disease and provide society an incalculable economic benefit. Allo-priming healthy elderly adults is proposed to provide universal protection from progression of any type of viral infection, including protection against progression of the current outbreak of COVID-19 infection, and any future variants of the causative SARS-CoV-2 virus or the next 'Disease X'. Allo-priming is an alternative approach for the COVID-19 pandemic that provides a back-up in case vaccination strategies to elicit neutralizing antibody protection fails or fails to protect the vulnerable elderly population. The allo-priming is performed using activated, intentionally mismatched, ex vivo differentiated and expanded living Th1-like cells (AlloStim^®) derived from healthy donors currently in clinical use as an experimental cancer vaccine. Multiple intradermal injections of AlloStim^® creates a dominate titer of allo-specific Th1/CTL memory cells in circulation, replacing the dominance of exhausted memory cells of the aged immune system. Upon viral encounter, by-stander activation of the allo-specific memory cells causes an immediate release of IFN-ϒ, leading to development of an "anti-viral state", by-stander activation of innate cellular effector cells and activation of cross-reactive allo-specific CTL. In this manner, the non-specific activation of allo-specific Th1/CTL initiates a cascade of spatial and temporal immune events which act to limit the early viral titer. The release of endogenous heat shock proteins (HSP) and DAMP from lysed viral-infected cells, in the context of IFN-ϒ, creates of conditions for in situ vaccination leading to viral-specific Th1/CTL immunity. These viral-specific Th1/CTL provide sterilizing immunity and memory for protection from disease recurrence, while increasing the pool of Th1/CTL in circulation capable of responding to the next viral encounter.

CONCLUSION

Allo-priming has potential to provide universal protection from viral disease and is a strategy to reverse immunosenescence and counter-regulate chronic inflammation (inflammaging). Allo-priming can be used as an adjuvant for anti-viral vaccines and as a counter-measure for unknown biological threats and bio-economic terrorism.

Immune signatures associated with mortality differ in elderly populations from different birth cohorts and countries even within northern Europe

Since associations between lifespan and certain simple immune parameters such as T cell proliferative responses to mitogens were reported in the 1970´s, efforts to dissect out immune parameters correlating with morbidity and mortality have sought to define factors predicting individual longevity. Such "immune signatures" associating with defined clinical outcomes would represent biomarkers of "immunosenescence" that might also provide mechanistic insights into the ageing process. Because appropriate immune function is necessary for a healthy old age, a better understanding of immunosenescence contributing to frailty and death might allow interventions to improve personal and public health. Here, we discuss data from our studies in several different European countries and document significant differences between overtly similar populations. These findings draw attention to the marked variation even between presumably quite homogeneous populations, which may be due to the different birth cohorts studied in addition to numerous other variables. Thus, immunological parameters, and presumably many other factors, are sensitive to context-dependent variation, making it currently difficult to extrapolate biomarkers of longevity from any one human population to another.

Mitochondrial Aging: Is There a Mitochondrial Clock?

Fragmentation (fission) of mitochondria, occurring in response to oxidative challenge, leads to heterogeneity in the mitochondrial population. It is assumed that fission provides a way to segregate mitochondrial content between the "young" and "old" phenotype, with the formation of mitochondrial "garbage," which later will be disposed. Fidelity of this process is the basis of mitochondrial homeostasis, which is disrupted in pathological conditions and aging. The asymmetry of the mitochondrial fission is similar to that of their evolutionary ancestors, bacteria, which also undergo an aging process. It is assumed that mitochondrial markers of aging are recognized by the mitochondrial quality control system, preventing the accumulation of dysfunctional mitochondria, which normally are subjected to disposal. Possibly, oncocytoma, with its abnormal proliferation of mitochondria occupying the entire cytoplasm, represents the case when segregation of damaged mitochondria is impaired during mitochondrial division. It is plausible that mitochondria contain a "clock" which counts the degree of mitochondrial senescence as the extent of flagging (by ubiquitination) of damaged mitochondria. Mitochondrial aging captures the essence of the systemic aging which must be analyzed. We assume that the mitochondrial aging mechanism is similar to the mechanism of aging of the immune system which we discuss in detail.

An Appropriate Modulation of Lymphoproliferative Response and Cytokine Release as Possible Contributors to Longevity

The decrease in the proliferative response of lymphocytes is one of the most evident among the age-related changes of the immune system. This has been linked to a higher risk of mortality in both humans and experimental animals. However, long-lived individuals, in spite of optimally maintaining most of the functions of the immune system, also seem to show an impaired proliferative response. Thus, it was hypothesized that these individuals may have distinct evolution times in this proliferation and a different modulatory capacity through their cytokine release profiles. An individualized longitudinal study was performed on female ICR-CD1 mice, starting at the adult age (40 weeks old), analyzing the proliferation of peritoneal leukocytes at different ages in both basal conditions and in the presence of the mitogen Concanavalin A, for 4, 24 and 48 h of culture. The cytokine secretions (IL-2, IL-17, IL-1β, IL-6, TNF-α and IL-10) in the same cultures were also studied. Long-lived mice show a high proliferative capacity after short incubation times and, despite experiencing a functional decline when they are old, are able to compensate this decrease with an appropriate modulation of the lymphoproliferative response and cytokine release. This could explain their elevated resistance to infections and high longevity.

Immune Dysfunction in Aged Horses

The aging process in people is associated with changes in adaptive and innate immune responses. Similar changes occur in aged horses. Age-related progressive impairment in the ability to respond to pathogen challenge and an increased inflammatory reactivity may predispose geriatric horses to many diseases of old age. Specific recommendations for immune modification of older horses, including an age-appropriate vaccination schedule, are not currently available. In addition, the effect of old age on risk of infectious disease is poorly documented. More work is needed to better understand the interactions of age on immunity, vaccine response, and disease risk in horses.

Markers of T-cell senescence and physical frailty: insights from Singapore Longitudinal Ageing Studies

BACKGROUND

Elderly individuals have an eroded immune system but whether immune senescence is implicated with the development of frailty is unknown. The underlying immune mechanisms and the link between markers of senescence and physical frailty is not well established.

METHODS

We explored the association of specific T-cell subset markers of immune differentiation and senescence on CD4⁺ and CD8⁺ cells (CD28^-, CD27^- and CD57⁺) and the immune risk profile (inverted CD4/CD8 ratio <1) with physical frailty among 421 participants who were frail (N=32), prefrail (N=187) and robust (N=202) in the Singapore Longitudinal Ageing Study cohort.

RESULTS

In ordinal logistic regression models relating tertile category rank scores of immune biomarker with frailty status (robust, prefrail and frail), CD8⁺CD28^-CD27⁺ (odds ratio (OR)=1.35, P=0.013), CD4⁺CD28^-CD27⁺ (OR=1.29, P=0.025), CD8⁺CD28^- (OR=1.31, P=0.022), and CD4/CD8 ratio (OR=1.27, P=0.026) were positively associated with frailty, controlling for age, sex and multimorbidity. CD4/CD8 ratio less than one was not associated with frailty (OR=0.84, P=0.64). In stepwise multinomial logistic regression controlling for age, sex and comorbidity, only CD8⁺CD28^-CD27⁺ was the independent predictor of prefrailty: highest tertile of the immune marker significantly predicted prefrailty (versus low tertile, OR=1.72, P=0.037) and frailty (OR=2.56, P=0.06).

CONCLUSION

The study supports the hypothetical role of immune senescence in physical frailty, particularly in regard to the observed loss of CD28 expression from both CD8⁺ cells and CD4⁺ cells, but not for CD27 or CD4/CD8 ratio as a marker of senescence. The potential of CD8⁺CD28^-CD27⁺ as a biological marker of frailty should be further investigated in prospective studies.

Genome-wide miRNA signatures of human longevity

Little is known about the functions of miRNAs in human longevity. Here, we present the first genome-wide miRNA study in long-lived individuals (LLI) who are considered a model for healthy aging. Using a microarray with 863 miRNAs, we compared the expression profiles obtained from blood samples of 15 centenarians and nonagenarians (mean age 96.4 years) with those of 55 younger individuals (mean age 45.9 years). Eighty miRNAs showed aging-associated expression changes, with 16 miRNAs being up-regulated and 64 down-regulated in the LLI relative to the younger probands. Seven of the eight selected aging-related biomarkers were technically validated using quantitative RT-PCR, confirming the microarray data. Three of the eight miRNAs were further investigated in independent samples of 15 LLI and 17 younger participants (mean age 101.5 and 36.9 years, respectively). Our screening confirmed previously published miRNAs of human aging, thus reflecting the utility of the applied approach. The hierarchical clustering analysis of the miRNA microarray expression data revealed a distinct separation between the LLI and the younger controls (P-value < 10(-5) ). The down-regulated miRNAs appeared as a cluster and were more often reported in the context of diseases than the up-regulated miRNAs. Moreover, many of the differentially regulated miRNAs are known to exhibit contrasting expression patterns in major age-related diseases. Further in silico analyses showed enrichment of potential targets of the down-regulated miRNAs in p53 and other cancer pathways. Altogether, synchronized miRNA-p53 activities could be involved in the prevention of tumorigenesis and the maintenance of genomic integrity during aging.

Enhancement of natural killer cell activity of aged mice by modified arabinoxylan rice bran (MGN-3/Biobran)

The present study is aimed to examine the possibility of enhancement of natural killer (NK) cell activity in aged C57BL/6 and C3H mice using MGN-3, a modified arabinoxylan from rice bran. Intraperitoneal injection of MGN-3 (10 mg kg−1 per day) caused a remarkable increase in the peritoneal NK activity as early as 2 days (35.2 lytic units), and the level remained elevated through day 14. The control aged mice had a level of 5.8 lytic units. Enhancement in NK activity was associated with an increase in both the binding capacity of NK cells to tumour targets and in the granular content as measured by BLT-esterase activity. Treatment did not alter the percentage of peritoneal NK cells. Data showed that peritoneal macrophages inhibit NK activity. In conclusion, MGN-3 enhances murine NK activity of aged mice and may be useful for enhancing NK function in aged humans.

Age-related alterations of gene expression patterns in human CD8+ T cells

Aging is associated with progressive T-cell deficiency and increased incidence of infections, cancer and autoimmunity. In this comprehensive study, we have compared the gene expression profiles in CD8+ T cells from aged and young healthy subjects using Affymetrix microarray Human Genome U133A-2 GeneChips. A total of 5.2% (754) of the genes analyzed had known functions and displayed statistically significant age-associated expression changes. These genes were involved in a broad array of complex biological processes, mainly in nucleic acid and protein metabolism. Functional groups, in which downregulated genes were overrepresented, were the following: RNA transcription regulation, RNA and DNA metabolism, intracellular (Golgi, endoplasmic reticulum and nuclear) transportation, signaling transduction pathways (T-cell receptor, Ras/MAPK, JNK/Stat, PI3/AKT, Wnt, TGFbeta, insulin-like growth factor and insulin), and the ubiquitin cycle. In contrast, the following functional groups contained more up-regulated genes than expected: response to oxidative stress and cytokines, apoptosis, and the MAPKK signaling cascade. These age-associated gene expression changes may be responsible for impaired DNA replication, RNA transcription, and signal transduction, possibly resulting in instability of cellular and genomic integrity, and alterations of growth, differentiation, apoptosis and anergy in human aged CD8+ T cells.

Immune receptor signaling, aging and autoimmunity

Aging is associated with a myriad of changes including alterations in glucose metabolism, brain function, hormonal regulation, muscle homeostasis and the immune system. Aged dividuals, generally still defined as over 65 years old, differ from middle-aged or young donors in many features of the immune system. The major observation is that the elderly population is not able to cope with infections as well as younger adults and recovery generally takes longer. Moreover, some diseases first appear with advancing age and are likely associated with dysfunction of the immune system. Thus, Alzheimer's disease, atherosclerosis, type II diabetes and some autoimmune disorders are linked to changes in immune function. One major immune cell population implicated as being responsible for the initiation and chronicity of immune dysfunction leading to diseases or immunosuppression is the T-cell. Although many changes in B-cell and innate immune function in aging are associated with the appearance of disease, they are not as well studied and clearly demarcated as changes in the T-cell compartment. The adaptive immune system is coordinated by T-cells, the activation of which is required for the initiation, maintenance and termination of responses against pathogens. Changes in the expression and functions of the T-cell receptor (TCR) for antigen and its co-receptors are closely associated with immunosenescence. Certain similar changes have also been found in some other disease states, e.g., rheumatoid arthritis, systemic lupus erythematosus and cancer. In this chapter, we will summarize our knowledge about multichain immune recognition receptor signaling, mainly the TCR, in aging and autoimmune diseases.

Characterization of intrinsic and extrinsic risk factors for celery allergy in immunosenescence

Recent studies indicated an underestimation of allergies in elderly. In our experimental food allergy model of protein feeding under acid-suppression we aimed to assess whether food allergy can be induced in immunosenescent mice. Furthermore, the impact of gastric digestion on celery allergenicity was evaluated in aged patients. Measurements of serum zinc and iron levels in senescent and adult BALB/c mice for definition of the nutritional status indicated a possible alteration of the immune response in the aged animals due to reduced zinc and iron levels. Feedings of mice with digestion-sensitive celery proteins under physiological gastric conditions induced IgG1 and IgG2a in the aged and preferentially IgG1 in the adult animals. In contrast, incomplete digestion due to acid-suppression rendered celery-specific IgE, positive skin tests and elevated IL-5 levels in both age groups. Also in aged celery allergic patients (mean age 72 years) properly digested celery showed decreased capacity to bind and crosslink IgE as evaluated by skin tests and IgE immunoblot. Thus, in the geriatric murine model, celery allergy was induced only if gastric digestion was hindered. Accordingly, gastric proteolysis decreased in vitro and in vivo IgE-reactivity against celery proteins in aged allergic patients.

Systematic expression profiling of innate immune genes defines a complex pattern of immunosenescence in peripheral and intestinal leukocytes

Immunosenescence is characterized by a quantitative decline of adequate immune responses, which renders the elderly individual particularly susceptible to bacterial, viral and fungal pathogens. Whereas changes of the aging adaptive immune system (for example, reduced immunoglobulin secretion) have been extensively characterized, alterations of the innate immune system are still poorly understood. The aim of the present study was to systematically examine mRNA expression levels of innate immune genes and proinflammatory cytokines in peripheral and intestinal leukocytes of subjects of different ages. In both, whole blood samples and in colonic biopsies most of the Toll-like receptors (TLRs) and nucleotide-binding and oligomerization domain-like receptors (NLRs) transcript levels were significantly downregulated in elderly subjects (90-99 years). Older individuals, when compared to the younger, exhibited an increased expression and/or secretion of proinflammatory cytokines by peripheral and intestinal leukocytes as well as an increased level of nuclear factor-kappaB activation in colonic biopsies. The observed downregulation of TLRs and NLRs during the aging process may contribute to the lack of effective recognition of invading pathogens or the commensal flora. This effect results in aberrant secondary immune cell activation and could significantly contribute to morbidity and mortality at advanced age.

Thymic output, ageing and zinc

The role of the thymus is vital for orchestration of T-cell development and maturation. With increasing age the thymus undergoes a process of involution which results in a reduction in thymic size, function and output. Until relatively recent it was not feasible to accurately measure the magnitude of age-related loss of thymic function. With the discovery of T-cell receptor excision circles (TRECs), which are the stable by-products of the newly generated T-cells, it is now possible to quantitatively measure the extent of thymic output. This review examines the available data on immune function and zinc deficiency and places them in the context of the aims of the ZINCAGE project which include the evaluation of the role played by zinc in maintaining thymic output in healthy elderly individuals.

Cell-mediated immunosenescence in birds

The phytohaemagglutinin (PHA) skin test response, used to assess cell-mediated immunity, is known to vary with many social and energetic factors, but the effects of age have received little attention. We found that the PHA response of immature birds was lower than those of the youngest breeding adults and were decreased in adults. Whenever possible, age should be included as a covariate when the PHA skin test is used to assess immunocompetence in ecological immunology. The rate of decline in PHA response differed between species and was inversely correlated with survival. The decrease in the PHA response averaged 57% over an average 80% of the maximum life span, but the absolute rate varied with species lifespan such that the short-lived species showed a greater loss per year than the long-lived species. This link between declining immune function and survival may reflect differences in resource partitioning between species, and suggests that selection may act on investment in immune function to influence maximum life span.

Increasing T-cell age reduces effector activity but preserves proliferative capacity in a murine allogeneic major histocompatibility complex-mismatched bone marrow transplant model

Aging of T cells is characterized by a series of alterations in surface antigen expression and a concomitant decline in functional activity in many assays. We have extended this analysis by comparing the ability of T cells from mice of different ages to cause graft-versus-host disease (GVHD) by using a parent into F(1) model (C57BL/6 T cells into C57BL/6 x C3H host animals). Young (3-5 months), adult (12-14 months), or old (19-24 months) T cells were introduced into irradiated F(1) hosts. Animals that had undergone transplantation were assessed for clinical and pathologic evidence of GVHD and for survival. At a given T-cell dose (2 x 10(6) cells), there was a T-cell (donor) age-dependent decline in severity of GVHD, with all recipients of young T cells succumbing to lethal GVHD, 75% of recipients of adult T cells succumbing, and no deaths occurring among recipients of old T cells. In vivo CD4 T-cell expansion was greater for young than old T-cell groups after transplantation, whereas old CD8 cells showed enhanced in vivo expansion compared with young cells. Among CD4 and CD8 cells, the T-cell receptor repertoire, surface antigen expression on activated cells, and homing receptor function were similar for all ages after expansion in vivo. The progeny of old T cells reisolated after transplantation expressed type 1 cytokines (interferon-gamma and tumor necrosis factor-alpha) at a lower frequency than young cells and had decreased cytolytic function against H-2(k)-bearing target cells. This provides a partial explanation for the decreased GVHD. Carboxyfluorescein diacetate succinimidyl ester labeling of transplanted cells showed comparable rates of proliferation when comparing GVHD-competent (12 months) and GVHD-incompetent (19 months) T cells in both syngeneic and F(1) host animals. We suggest that the lack of effector activity demonstrated by old T cells in vivo is a reflection of a cell-autonomous defect downstream of signals required for antigen-driven proliferation.

Age-related CD8 T cell clonal expansions constrict CD8 T cell repertoire and have the potential to impair immune defense

Peripheral T cell diversity is virtually constant in the young, but is invariably reduced in aged mice and humans. CD8+ T cell clonal expansions (TCE) are the most drastic manifestation of, and possible contributors to, this reduced diversity. We show that the presence of TCE results in reduced CD8+, but not CD4+, T cell diversity, and in functional inability to mobilize parts of the CD8+ T cell repertoire affected by TCE. In the model of herpes simplex virus (HSV)-1 infection of B6 mice, >90% of the responding CD8+ T cells use Vbeta10 or Vbeta8 and are directed against a single glycoprotein B (gB498-505) epitope, gB-8p. We found that old animals bearing CD8+ TCE within Vbeta10 or Vbeta8 families failed to mount an effective immune response against HSV-1, as judged by reduced numbers of peptide-major histocompatibility complex tetramer+ CD8 T cells and an absence of antiviral lytic function. Furthermore, Vbeta8 TCE experimentally introduced into young mice resulted in lower resistance to viral challenge, whereas Vbeta5+ TCE induced in a similar fashion did not impact viral resistance. These results demonstrate that age-related TCE functionally impair the efficacy of antiviral CD8+ T cell immunity in an antigen-specific manner, strongly suggesting that TCE are not the mere manifestation of, but are also a contributing factor to, the immunodeficiency of senescence.

T cell subsets and mortality in older community-dwelling women

The relationship between specific T cell subset alterations and mortality has not been well characterized in older adults. The specific aim was to determine whether specific T cell subsets are associated with an increased risk of death. We conducted a case-control study of T cell subsets (CD4+ and CD8+ T cells, and subsets of these cells defined by expression or non-expression of CD28, CD45RA, and CD45RO) nested within two complementary prospective cohorts of women aged 65 and over living in the community, the Women's Health and Aging Studies (WHAS). Cases consisted of 61 women who died during 5 years of follow-up, and controls consisted of 61 women matched by age, frailty, and morbidities who survived during 7 years of follow-up. There were no significant differences between cases and controls in any of the T cell subsets studied. When analyses were stratified by frailty status, these data suggest that CD8+CD28- lymphocyte counts were significantly higher among women who were frail compared with pre-frail and non-frail women.

Laparoscopic colorectal surgery modifies risk factors for postoperative morbidity

PURPOSE

The aim of this study was to evaluate whether laparoscopic colorectal surgery can modify the risk factors for the occurrence of postoperative morbidity.

METHODS

A total of 384 consecutive patients with colorectal disease were randomized to laparoscopic resection (n = 190) or open resection (n = 194). On admission, demographics, comorbidity, and nutritional status were recorded. Operative variables, patient outcome, and length of stay were also recorded. Postoperative complications were registered by four members of staff not involved in the study.

RESULTS

The overall morbidity rate was 27.1 percent, with the rate in the laparoscopic group (18.7 percent) being less than that in the open group (31.5 percent; P = 0.003). Patients who underwent laparoscopic resection had a faster recovery of bowel function (P = 0.0001) and a shorter length of stay (P = 0.0001). In the whole cohort of patients, multivariate analysis identified open surgery (P = 0.003), duration of surgery (P = 0.01), and homologous blood transfusion (P = 0.01) as risk factors for postoperative morbidity. In the open group, blood loss (P = 0.01), homologous blood transfusion (P = 0.01), duration of surgery (P = 0.009), weight loss (P = 0.06), and age (P = 0.08) were related to postoperative morbidity. In the laparoscopic group the only risk factor identified was duration of surgery (P = 0.005).

CONCLUSION

In the laparoscopic group, both postoperative morbidity and length of stay were significantly reduced and most risk factors for postoperative morbidity disappeared.

Hematopoietic stem cells mobilization and immune response in tumor-bearing mice

INTRODUCTION

Malignant diseases are known to modulate the number and function of myeloid, erythroid, and lymphoid cells. Since these cells are derived from hematopoietic stem cells (HSC), it is not clear if the observed effects of cancer on such cells are direct or indirect via stem cells. The purpose of this study was to evaluate the effect of breast cancer upon the levels and activity of peripheral blood hematopoietic stem cells.

MATERIALS AND METHODS

Four weeks following the establishment of 4T1 breast cancers in BALB/c mice, the animals were killed, blood and spleen harvested, and processed for light density mononuclear cells. Colony forming unit in culture assay was used to determine the activity of HSCs. Flow cytometry was used to determine the levels of lineage negative HSCs expressing c-kit and Sca-1 antigen (Lin c-kitSca-1). Mitogenic, cytotoxic and ELISPOT assays were used to evaluate functional properties of cells. Plasma cytokine levels were determined with ELISA assay.

RESULTS

In tumor-bearing mice, there was a 2- and 4-fold increase in the levels and proliferative capacity of HSCs, respectively, compared with controls. Contemporaneously, there was a 13-fold increase in plasma G-CSF in tumor-bearing animals compared with controls (0.225 ng/ml versus 3.0 ng/ml). Furthermore, the number of interferon gamma-secreting cells was significantly increased in tumor-bearing animals. Concurrently, cytotoxic activity of NK cells was significantly increased in tumor-bearing animals as compared with controls (22.4 +/- 10.6 versus 10.3 +/- 2.95; P < 0.05).

SUMMARY

These results suggest that (1) breast cancer mobilizes hematopoietic stem cells in mice presumably through G-CSF production, and (2) that such cancer-mobilized stem cells give rise to immune cell lineages which are functionally hyperactive in their cytotoxic activities. Such cells could be expected to have appreciable therapeutic benefit in terms of cancer cell cytotoxic activity when used as part of stem cell transplantation therapy in cancer patients.

Immunological markers contributing to successful aging in Bulgarians

In order to clarify immunogenetic markers contributing to successful aging, HLA and cytokine gene profiles were analyzed in healthy elderly Bulgarians. Family segregation analysis was performed to define combined effect of haplotypes and immunophenotype profiles. The results of this study did not reveal any statistically significant allele and haplotype frequency differences between elderly and control group. In families with two generations longevity members we did not observed HLA alleles and haplotypes associated with autoimmunity. IL-10 genotype -1082G/A, -819 C/C, -592 C/C, related to the intermediate production, was positively associated, while genotype -1082A/A, -819 C/T, -592 C/A, related to the low level of production, was negatively associated with longevity in Bulgarians. This effect was modulated by IL-6 and IFNgamma genotypes associated with the low level of these pro-inflammatory cytokines. Immunophenotypic studies indicated lower relative and absolute numbers of CD3+8+, CD8+28+ and CD8+57+ cells in elderly people. Analysis in families showed that although most pronounced in the elderly group, lower numbers of CD8+ T cells were also found in middle aged and young members of the families compared to the age matched controls. A progressive CD8+28+ cell subsets decline was seen with aging. In addition, we did not observed the 'immune risk phenotype' which is a marker of an increased inflammatory activity. Based on the results of this study, it seems reasonable to suggest that a combination of specific immunogenetic and immunophenotype profiles could contribute to the successful aging and to maintaining healthy status in elderly.

Replicative senescence of CD8 T cells: effect on human ageing

Elderly persons have been exposed to a myriad of pathogens over their lifespan. This life-long immunological history leads, in some cases, to the generation of expanded populations of memory CD8 T cells that have reached the end stage of replicative senescence. In cell culture, CD8 T cells that are subjected to repeated rounds of antigen-driven proliferation eventually show irreversible cell cycle arrest, permanent and complete loss of CD28 gene expression, apoptosis resistance, reduced gene transcription of the major stress protein in response to heat shock, and shortened telomeres compared to their CD28-expressing progenitors. Clinical studies have documented that high proportions of CD8 T cells that lack CD28 are correlated with reduced antibody response to influenza vaccination and are also an immune marker of increased risk of mortality in persons greater than 80 years of age. In addition, CD8 T cells lacking CD28 expression have been documented to have suppressive influences on immune function. Thus, senescent CD8 T cells may affect immune function both directly and indirectly by modulating other immune cell types. The potential role of senescent T cells in bone homeostasis is suggested as a potentially fruitful area for future investigation. The patterns of cytokine changes observed during the progression to senescence in cell culture are consistent with this possibility, and T cells producing these same cytokines have, in fact, been identified within the bone marrow in murine models of osteoporosis. Interestingly, CD8 T cells with markers of replicative senescence are correlated with increased osteoporotic fractures in the elderly. Thus, senescent CD8 T cells are associated with a variety of deleterious health-related outcomes, suggesting that these cells may exert pleiotropic negative effects on both immune and non-immune organ systems during ageing.

Serum and lymphocyte levels of heat shock protein 70 in aging: a study in the normal Chinese population

Heat shock proteins (Hsps) have been reported to play an important role in both physiological and pathological processes. Hsps also may serve as biomarkers for evaluating disease states and exposure to environmental stresses. Whether Hsp levels in serum and lymphocytes are correlated with age and sex is largely unknown. In this study, we analyzed serum Hsp70 (the most abundant mammalian Hsp) levels by using Western dot blot in 327 healthy male donors aged between 15 and 50 years. We also investigated the association between Hsp70 levels and age in lymphocytes of 80 normal individuals aged between 40 and 77 years because various chronic diseases increase after the age of 40 years. Our data showed that serum Hsp70 levels were positively correlated with age in subjects aged between 15 and 30 years (P < 0.05) but negatively correlated with age in subjects aged between 30 and 50 years (P < 0.05). Serum Hsp70 levels were the highest in individuals aged between 25 and 30 years among all age groups. In the lymphocyte study there also was a significant age-related decrease in Hsp70 levels in lymphocytes of individuals older than 40 years. The Hsp70 levels were negatively correlated with age (r = -3.708, P < 0.0001) but not with sex (r = -10.536, P = 0.452). This suggests that both serum and lymphocyte Hsp70 levels are age-related and that these may be linked to age-related stress. Thus, age is an important factor in using serum and lymphocyte Hsp70 as biomarkers to evaluate the disease states or exposure to environmental stresses (or both).

Ageing, autoimmunity and arthritis: Perturbations of TCR signal transduction pathways with ageing - a biochemical paradigm for the ageing immune system

It is widely accepted that cell-mediated immune functions decline with age, rendering an individual more susceptible to infection and possibly cancer, as well as to age-associated autoimmune diseases. The exact causes of T-cell functional decline are not known. One possible cause could be the development of defects in the transduction of mitogenic signals following TCR stimulation. This T-cell hyporesponsiveness due to defects of signalling through the TCR either from healthy elderly subjects or from individuals with autoimmune diseases such as rheumatoid arthritis or systemic lupus erythematosus results in an impaired ability to mount efficient immune responses and to maintain responsiveness to foreign antigens. This implies that a high proportion of autoreactive T cells might accumulate either intrathymically or in the periphery. T-cell anergy and differential TCR signalling could thus also be key players in the disruption of tolerance and the onset of autoimmune diseases. The increasing number of the elderly may lead to an increase of clinically important autoimmune diseases. We will review the signal transduction changes through the TCR-CD3 complex in T lymphocytes from healthy elderly subjects, which result in a modification of the activation of transcription factors involved in IL-2 gene expression leading to decreased IL-2 production. The putative contribution of altered T-cell signalling with ageing in the development of autoimmune diseases will be also discussed.

Relationship between the eosinophilia of bronchoalveolar lavage fluid (BALF) and the severity of pulmonary fibrosis induced by bleomycin in rats

A large number of studies have demonstrated that the presence of eosinophils in the lungs of patients with pulmonary fibrosis correlates with poor prognosis or resistance to therapy. However, direct evidence of the relationship between the influx of eosinophil and pulmonary fibrosis has not yet been described experimentally. In this article, pulmonary fibrosis was induced by different doses of bleomycin (BLM) and using different aged rats. On selected days afterwards, the lungs were lavaged and harvested for analyzing fibrosis, eosinophil influx and cytokine expression. There was a significant relationship between eosinophilia and the pulmonary fibrosis (r=0.98, p<0.01). In spite of the fact that there was no significant increase in hydroxyproline of the lung, eosinophil influxes of bronchoalveolar lavage fluid (BALF) was maximal 7 d after BLM administration. Moreover, there were similar patterns among transforming growth factor beta (TGF)-beta(1), hepatocyte growth factor (HGF) and eosinophil influx of BALF in that they were dependent on dose of BLM and age. These findings, taken together, have suggested the causal correlation of eosinophilia during the early stage with subsequent pulmonary fibrosis. The possible role of eosinophils in the pathogenesis of pulmonary fibrosis might contribute to not only TGF-beta(1) but also HGF production.

Influence of ageing, heat shock treatment and in vivo total antioxidant status on gene-expression profile and protein synthesis in human peripheral lymphocytes

Ageing results in a progressive, intrinsic and generalised imbalance of the control of regulatory systems. A key manifestation of this complex biological process includes the attenuation of the universal stress response. Here we provide the first global assessment of the ageing process as it affects the heat shock response, utilising human peripheral lymphocytes and cDNA microarray analysis. The genomic approach employed in our preliminary study was supplemented with a proteomic approach. In addition, the current study correlates the in vivo total antioxidant status with the age-related differential gene expression as well as the translational kinetics of heat shock proteins (hsps). Most of the genes encoding stress response proteins on the 4224 element microarray used in this study were significantly elevated after heat shock treatment of lymphocytes obtained from both young and old individuals albeit to a greater extent in the young. Cell signaling and signal transduction genes as well as some oxidoreductases showed varied response. Results from translational kinetics of induction of major hsps, from 0 to 24 h recovery period were broadly consistent with the differential expression of HSC 70 and HSP 40 genes. Total antioxidant levels in plasma from old individuals were found to be significantly lower by comparison with young, in agreement with the widely acknowledged role of oxidant homeostasis in the ageing process.

Stress-associated immunomodulation and its implications for responses to vaccination

The rapidly growing field of psychoneuroimmunology involves the elucidation of the complex interactions between the CNS, the endocrine system and the immune system and its effects on health. Although the mechanisms involved in this bidirectional communication is not yet fully understood, studies in psychoneuroimmunology have shown that stress, through the hypothalamic-pituitary-adrenal and the sympathetic-adrenal-medullary axes, can induce modulation of the immune system. In this review, we discuss human studies and animal models, which focus on psychological stress and its effects on the immune response to vaccination, emphasizing the implications of these effects on health.

Rejection and recipient age

In transplantation the risk of acute rejection decreases with recipient age. This is clearly illustrated in transplantation of a non-vascularised tissue, such as the cornea. In vascularised transplants, such as kidneys, acute rejection decreases with recipient age, but the phenomenon is obscured by the fact that chronic allograft nephropathy increases with age, and is further confounded by increased death from infectious disease and drug-related causes. The underlying cellular mechanisms responsible for this weakening of rejection are discussed, as is defective signal transduction leading to decreased activation of cells and decreased resistance to immunosuppressive drugs. This supports a view that less intensive immunosuppressive drug therapy is desirable in elderly recipients. Although pharmacokinetic studies are documented, there are no routine assays to measure efficacy of these drugs in individual patients. In summary, the decline in acute rejection with increasing recipient age may be due both to immunosenescence and decreased resistance to immunosuppressive drugs. Future assays to test these mechanisms could be used to tailor therapy to individual needs.

Influenza A virus specific T cell immunity in humans during aging

To study the decreasing responsiveness of the immune system during aging, influenza virus specific cellular immunity was investigated in a cohort of healthy blood donors between 18 and 70 years of age. The percentage of influenza A virus specific T cells was determined by flow cytometry and found not to change during aging. After stimulation with phorbol 12-myristate 13-acetate and ionomycin, an increase in the percentage of IFN-gamma and IL-4 producing CD8(+) T cells was observed during aging. In addition, the cytotoxic T lymphocyte (CTL) activity was investigated in two additional groups of five donors, 18-20 and 68-70 years of age. The lytic capacity of purified CD8(+) T cells, after in vitro stimulation of peripheral blood mononuclear cells with influenza A virus, seemed lower in 68- to 70-year-old donors than in 18- to 20-year-old donors. Therefore we conclude that the reduced CTL activity in the elderly is not the result of a lower frequency of virus-specific T cells, but more likely the result of impaired antigen-specific proliferation or lower lytic capacity of these cells.

The inhibition of calcium signaling in T lymphocytes from old mice results from enhanced activation of the mitochondrial permeability transition pore

Aging attenuates calcium signaling in T lymphocytes from old mice. Aging also attenuates the sustained elevation of cell free calcium by ionomycin, which is similar to the T cell receptor signal. In T lymphocytes from young mice, the ionomycin-induced elevation of cell free calcium was inhibited by collapsing the mitochondrial membrane potential by uncouplers and ionophores, and activation of the permeability transition. In T lymphocytes from old mice, the mitochondrial membrane potential was largely collapsed, but cyclosporin and N-methyl-val-4-cyclosporin, inhibitors of the permeability transition, restored the mitochondrial potential, as well as the ionomycin-induced elevation of cell free calcium. In addition, the generation of reactive oxygen species in the presence of mitochondrial electron transport inhibitors was relatively enhanced in T lymphocytes from old mice. The association between low rhodamine 123 fluorescence and attenuated calcium signaling in T lymphocytes from old mice is also shown to be a consequence of the collapsed mitochondrial potential. These results suggest that Ca2+ signaling is attenuated in T lymphocytes from old mice because of an enhanced activation of the permeability transition.

RANTES and MIP-1alpha production by T lymphocytes, monocytes and NK cells from nonagenarian subjects

While numerous previous studies have investigated age-related changes of cytokine production, little is known about chemokines, the importance of which in regulating immune response is becoming increasingly evident. In this study, a group of healthy subjects over 90 years old is compared to a group of young subjects, we evaluated the ability of monocytes, T lymphocytes and NK cells: (1) to produce RANTES and MIP-1alpha, either in basal conditions or after stimulation with, respectively, LPS, anti-CD3 MoAb and IL-2; (2) to express the corresponding chemokine receptors (CCR1, CCR3, CCR5). We demonstrate that: (a) monocytes, T lymphocytes and NK cells spontaneously produced detectable amounts of chemokines, both in young and old subjects; (b) monocyte-dependent RANTES and MIP-1alpha production induced by LPS was up-regulated in nonagenarian subjects as anti-CD3-induced secretion from T cells; (c) RANTES and MIP-1alpha production by IL-2 stimulated NK cells was reduced in elderly subjects; (d) CCR1, CCR3 and CCR5 were widely expressed on monocytes, but less expressed on T lymphocytes and NK cells. The diversity within PBMC might reflect their different states of activation and/or responsiveness, influencing the ability to develop rapid innate and long-lasting adaptive immune responses.

Age associated decline in CD25 and CD28 expression correlate with an increased susceptibility to CD95 mediated apoptosis in T cells

Immunosenescence is believed to contribute to increase susceptibility to infectious diseases and cancer in the elderly, and is caused mainly by changes in the T cell compartment. Longitudinal studies were undertaken to examine T cell surface receptor expression and apoptotic susceptibility using Staphylococcal enterotoxin B (SEB) activated human T cells as an in vitro model of an ageing T cell culture. An intracellular stain Carboxyfluorescein diacetate succinimidyl ester (CFSE) was used to assess the number of population divisions (PD) occurring in the ageing T cell culture. One major biomarker of aged T cells is a decrease in expression of CD28 and since this is an essential co-stimulatory molecule, its decreasing expression with age could compromise their activation and apoptotic capacity. Activation of T cells resulted in initial up-regulation of CD25, CD95 and CD28, although expression of CD25 and CD28 subsequently decreased with increasing PD. CD4 and CD8 T cells expressed similar CD25 profiles although CD28 expression was unique in each subset. CD4+ cells expressed the highest CD28 levels, and showed a gradual decline in expression with increasing PD, whereas CD8+ cells were low CD28 expressers, but did not appear to lose their expression as they aged. To determine T cell susceptibility to apoptosis via CD95/CD95-L interactions with increasing age, cells were challenged with CD95-L transfected CHO cells at various PD. Increased death was observed as they aged, which correlated with the decreased expression of activation markers CD25 and CD28.

Different IL-8 production by T and NK lymphocytes in elderly subjects

A gradual decline in the functional activity of the immune system is described with advancing age. The adaptive immune system seems the most severely affected, but some age-associated modifications also occurs in NK cells. Several studies investigated the age related changes of cytokine production, while little is known about chemokines, whose importance in regulating immune-response becomes even more evident. In this study we investigated whether the ability of T lymphocytes and NK cells to produce IL-8, either spontaneously or after activation, respectively with anti-CD3 monoclonal antibody or interleukin 2 (IL-2) was affected by age. We demonstrated that: (a) T lymphocytes and NK cells spontaneously produced detectable amounts of IL-8; (b) anti-CD3 stimulation of T lymphocytes significantly increased IL-8 production and the increment was more evident in the nonagenarian subjects; (c) similarly, IL-2 stimulation of NK cells rose the production of IL-8 but the amount produced by the old was lower than the one produced by the young group. Because of the co-stimulatory role of chemokines on NK responses and given the demonstrated importance of NK cells in defence against viral infections, the decreased production of IL-8 can be involved in the defective functional activity of NK cells from old subjects.

Sex dependent differences in physiological ageing in the immune system of lower airways in healthy non-smoking volunteers: study of lymphocyte subsets in bronchoalveolar lavage fluid and blood

BACKGROUND

Age related changes in the immune system have been studied frequently but a possible relation to sex has not, to our knowledge, previously been examined. The effect of age and sex on the composition of lymphocyte subsets in bronchoalveolar lavage (BAL) fluid and peripheral blood was therefore examined.

METHODS

Bronchoscopy with lavage was performed in 32 healthy non-atopic, non-smoking volunteers (16 women aged 26-63 years (mean 44) and 16 men aged 23-63 years (mean 39)). Cytospin preparations for differential counts of BAL fluid cells and surface antigen expression of lymphocytes from BAL fluid and blood were analysed by flow cytometry.

RESULTS

Most parameters in the BAL fluid changed with age in women. The percentage of CD4+ lymphocytes increased with age from a mean of 48 (SD10)% in women aged < or =40 years to 69 (11)% in women aged >43 years (p=0.001). The percentage of CD8+ lymphocytes tended to decrease with age and the CD4/CD8 ratio was 5.8 (1.2) in women aged >43 years compared with 2.1 (0.7) in those aged < or =40 years (p<0.0001). Women aged >43 years differed from men aged >43 years as well as from younger subjects of both sexes with respect to CD4+ cells and CD4/CD8 ratio, and from younger women with respect to CD8+ cells. There was no age related change in the CD4/CD8 ratio in blood. No sex related differences were seen in the blood or BAL fluid of adults below the age of 40 years.

CONCLUSIONS

The composition of lymphocytes with different phenotypes in the lower respiratory tract changes with age in women but not in men. This may have implications for some clinical conditions such as chronic dry cough which are observed predominantly in women.

Effects of losartan treatment on T-cell activities and plasma leptin concentrations in primary hypertension

Recent evidence shows that leptin may contribute to elevated blood pressure (BP) and interact with the renin-angiotensin-aldosterone and cellular immune systems. Altered T-cell activities and changes in T-cell subset ratios have also been reported in hypertension. However, little is known about the effects of AT1-receptor antagonism on T-cell activities and plasma leptin concentrations in primary hypertension. We have, therefore, investigated the relationship between leptin and T-cell activities and the effect of an AT1-receptor antagonist, losartan, in primary hypertension. Twenty recently-diagnosed and untreated young adults (11 males and 9 females, age; 39.9+/-7.6 years, range 23-49 years, BMI; 27.6+/-3.7kg/m2) and 20 normotensive healthy, age-, sex- and BMI-matched controls were studied. The [3H]-thymidine uptakes of cultured lymphocytes were determined, both spontaneously and after stimulation with phytohaemagglutinin. The tests were performed before and after three months of treatment with losartan. The results indicate that the blastogenic responses of T-cells to phytohaemagglutinin are significantly higher in the patient group compared with controls (p=0.02). After normalisation of BP, T-cell responses were significantly reduced and were lower than in the controls (p=0.01). Pretreatment plasma leptin levels were significantly higher in hypertensives than in controls (p=0.01). However, losartan treatment had no significant effect on leptin concentrations; moreover, no correlation between leptin levels and T-cell activity was found. Our data show that plasma leptin levels and T-cell activity are markedly enhanced in untreated essential hypertension and that the alteration of T-cell activity is not related to plasma leptin levels. Antihypertensive treatment with losartan decreases T-cell activities but does not influence plasma leptin levels. We conclude that leptin levels are not affected by AT1-receptor blockade and are not related to T-cell activity.

Changes in the expression of surface receptors on lymphocyte subsets in the elderly: quantitative flow cytometric analysis

The immunophenotype of circulating lymphocytes, including the intensity expression of surface receptors, changes with ageing. Until now, no results of systematic studies on age-dependent changes with respect to the expression of the major lymphocyte surface receptors in healthy elderly subjects have been reported. In order to identify age-related changes in both representation and immunophenotype of lymphocyte populations, we investigated, by means of triple-color whole-blood immunostaining and quantitative flow cytometry, the percent values and the absolute numbers, as well as the levels of surface antigen expression or antigen molecules per cell (ABC values x 10(3)), of different peripheral blood lymphocyte subsets from 23 healthy elderly subjects and 13 young donors. Naive (CD45RA+CD3+) T cells, total B cells, and CD5+ B lymphocytes are decreased (22%, 6%, 0.8% vs. 30%, 12%, 1.4%, respectively), whereas activated (HLA-DR+CD3+) and memory (CD45RO+CD3+) T cells, CD3+CD7- T lymphocytes, and lymphocytes expressing the NK marker CD56 are expanded in the elderly (2%, 53%, 13%, 6% vs. 0.8%, 45%, 8%, 8%, respectively). Moreover, T lymphocytes from elderly individuals express lower CD3 (61 +/- 10) compared to young (69 +/- 10). Considering the different T-cell populations, CD3 antigen is respectively decreased on CD45RO+ T cells (55 +/- 14 vs. 66 +/- 14) and up-regulated on CD56+ T lymphocytes (62 +/- 21 vs. 45 +/- 20). Increased CD8 expression characterizes CD3+CD7- lymphocytes (70 +/- 34 vs. 44 +/- 17) while HLA-DR on activated T cells is lower in old (39 +/- 7) than young (46 +/- 9) donors. CD7 is down-regulated both in T (22 +/- 3 vs. 28 +/- 3) and NK (48 +/- 18 vs. 71 +/- 18) cells, whereas CD2 expression, unchanged on NK cells, is up-regulated on T lymphocytes (54 +/- 10 vs. 41 +/- 8). Age-related changes in B-cell antigen expressions were also found: CD20 is increased (124 +/- 23 vs. 105 +/- 16) whereas, despite the unchanged CD5 expression of T cells, CD5 intensity on the B-cell subset co-expressing this antigen is higher in old (49 +/- 37) than in young (22 +/- 4) people. The observed changes in the expression of functionally important cellular receptors can contribute to the remodeling of immune function characteristic of the elderly. Moreover, since quantitative flow cytometry is becoming widely employed in clinical practice, our results also contribute to the assessment of specific age-dependent antigen expression changes to be considered for diagnostic approaches in the elderly.

Sex dependent differences in physiological ageing in the immune system of lower airways in healthy non-smoking volunteers: study of lymphocyte subsets in bronchoalveolar lavage fluid and blood

BACKGROUND

Age related changes in the immune system have been studied frequently but a possible relation to sex has not, to our knowledge, previously been examined. The effect of age and sex on the composition of lymphocyte subsets in bronchoalveolar lavage (BAL) fluid and peripheral blood was therefore examined.

METHODS

Bronchoscopy with lavage was performed in 32 healthy non-atopic, non-smoking volunteers (16 women aged 26–63 years (mean 44) and 16 men aged 23–63 years (mean 39)). Cytospin preparations for differential counts of BAL fluid cells and surface antigen expression of lymphocytes from BAL fluid and blood were analysed by flow cytometry.

RESULTS

Most parameters in the BAL fluid changed with age in women. The percentage of CD4+ lymphocytes increased with age from a mean of 48 (SD10)% in women aged ⩽40 years to 69 (11)% in women aged >43 years (p=0.001). The percentage of CD8+ lymphocytes tended to decrease with age and the CD4/CD8 ratio was 5.8 (1.2) in women aged >43 years compared with 2.1 (0.7) in those aged ⩽40 years (p<0.0001). Women aged >43 years differed from men aged >43 years as well as from younger subjects of both sexes with respect to CD4+ cells and CD4/CD8 ratio, and from younger women with respect to CD8+ cells. There was no age related change in the CD4/CD8 ratio in blood. No sex related differences were seen in the blood or BAL fluid of adults below the age of 40 years.

CONCLUSIONS

The composition of lymphocytes with different phenotypes in the lower respiratory tract changes with age in women but not in men. This may have implications for some clinical conditions such as chronic dry cough which are observed predominantly in women.

Immune effects of hormone replacement therapy in post-menopausal women

Hormone replacement therapy (HRT) confers many health benefits to post-menopausal women. Despite links between estrogen and immune function prior to menopause, the immune status of women receiving HRT has not been rigorously investigated. This case-control study uses clinical laboratory assessment, flow cytometry, and functional assays to measure immune function. Participants included 27 post-menopausal women taking estrogen/progestin combinations, and 22 post-menopausal women not receiving HRT. Compared to the (-)HRT group, the (+)HRT group had more B-cells (p<0.05), higher mitogen-induced T-cell proliferation (p<0.05), and higher levels of induced TNF-alpha (p<0.05). There was a trend towards a lower proportion of CD4+ T-cells expressing the activation marker CD25+ (p<0.10). These findings represent a reversal of immune alterations associated with normal aging, suggesting that preservation or improvement of immune function may be associated with the use of HRT.

Age-related change in peripheral blood T-lymphocyte subpopulations and cytomegalovirus infection in the very old: the Swedish longitudinal OCTO immune study

Results from the previous times (Times 1-3) of the Swedish longitudinal OCTO immune study indicated that a combination of high CD8 and low CD4 percentages and poor T-cell proliferation in PBL was associated with a higher 2-year mortality in a sample of very old Swedish individuals. The combination of immune parameters was closely related to an inverted CD4/CD8 ratio. In the present study at Time 4 (T4) results are reported from the final follow-up of this longitudinal study, 8 years after it was initiated in 1989. An additional goal at this time point was to examine the immune system alterations in the very old in relation to evidence of lymphocyte activation and cytomegalovirus antibody status. In the present study immune system changes were identified that suggest a loss of T-cell homeostasis, as reflected by a decrease in the number of CD4 cells and a very significant increase in the number of CD8 cells in individuals with an inverted CD4/CD8 ratio. When considered over the duration of the OCTO study the inversion occurred in a high percentage (32%) of the individuals included in the original sample and was associated with non-survival. At T4 the changes were apparent in a number of the T-cell subsets, but particularly in the CD8+CD28-and CD57+ subsets. T-cell activation was significantly associated with the inversion of the CD4/CD8 ratio. In this very old sample the subset alterations were associated with evidence of cytomegalovirus (CMV) infection.

Age-related changes in the neuropeptide Y effects on murine lymphoproliferation and interleukin-2 production

Neuropeptide Y (NPY) modulates several aspects of the immune response but it is not known whether NPY responsiveness is altered with aging. In this work, the in vitro effect of NPY at concentrations ranging from 10(-)(14) M to 10(-)(7) M on lymphoproliferation has been studied in spleen, axillary node and thymus leukocytes from young, adult, mature and old BALB/c mice. The spontaneous proliferation of spleen lymphocytes from young mice was significantly stimulated by NPY. In response to the mitogen Con A, lymphoproliferation and IL-2 release by lymphocytes were inhibited significantly by NPY, these effects disappearing with aging. The results show that NPY is a modulator of lymphoproliferation and that this effect disappears progressively with age. Moreover, this regulatory role of NPY may be carried out through a decrease in IL-2 production.

Changes in immune function with age

Aging is associated with a decline in immune function in humans and animals. The primary defects appear to reside in the T-cell compartment. Improving understanding of the mechanisms underlying the general decline in immune functions with age may enhance our ability to prevent and treat age-associated illnesses. Development of biomarker(s) of immune senescence may eventually help clinicians to identify subpopulations of the elderly who are at risk for infections, malignancies, and possibly autoimmune diseases.