The immune status of healthy centenarians

SuperAgers and centenarians, dynamics of healthy ageing with cognitive resilience

Graceful healthy ageing and extended longevity is the most desired goal for human race. The process of ageing is inevitable and has a profound impact on the gradual deterioration of our physiology and health since it triggers the onset of many chronic conditions like dementia, osteoporosis, diabetes, arthritis, cancer, and cardiovascular disease. However, some people who lived/live more than 100 years called 'Centenarians" and how do they achieve their extended lifespans are not completely understood. Studying these unknown factors of longevity is important not only to establish a longer human lifespan but also to manage and treat people with shortened lifespans suffering from age-related morbidities. Furthermore, older adults who maintain strong cognitive function are referred to as "SuperAgers" and may be resistant to risk factors linked to cognitive decline. Investigating the mechanisms underlying their cognitive resilience may contribute to the development of therapeutic strategies that support the preservation of cognitive function as people age. The key to a long, physically, and cognitively healthy life has been a mystery to scientists for ages. Developments in the medical sciences helps us to a better understanding of human physiological function and greater access to medical care has led us to an increase in life expectancy. Moreover, inheriting favorable genetic traits and adopting a healthy lifestyle play pivotal roles in promoting longer and healthier lives. Engaging in regular physical activity, maintaining a balanced diet, and avoiding harmful habits such as smoking contribute to overall well-being. The synergy between positive lifestyle choices, access to education, socio-economic factors, environmental determinants and genetic supremacy enhances the potential for a longer and healthier life. Our article aims to examine the factors associated with healthy ageing, particularly focusing on cognitive health in centenarians. We will also be discussing different aspects of ageing including genomic instability, metabolic burden, oxidative stress and inflammation, mitochondrial dysfunction, cellular senescence, immunosenescence, and sarcopenia.

Immunosenescence as a convergence pathway in neurodegeneration

Immunity refers to the body's defense mechanism to protect itself against illness or to produce antibodies against pathogens. Senescence is a cellular phenomenon that integrates a sustainable growth restriction, other phenotypic abnormalities and including a pro-inflammatory secretome. It is highly involved in regulating developmental stages, tissue homeostasis, and tumor proliferation monitoring. Contemporary experimental reports imply that abolition of senescent cells employing evolved genetic and therapeutic approaches augment the chances of survival and boosts the health span of an individual. Immunosenescence is considered as a process in which dysfunction of the immune system occurs with aging and greatly includes remodeling of lymphoid organs. This in turn causes fluctuations in the immune function of the elderly that has strict relation with the expansion of autoimmune diseases, infections, malignant tumors and neurodegenerative disorders. The interaction of the nervous and immune systems during aging is marked by bi-directional influence and mutual correlation of variations. The enhanced systemic inflammatory condition in the elderly, and the neuronal immune cell activity can be modulated by inflamm-aging and peripheral immunosenescence resulting in chronic low-grade inflammatory processes in the central Nervous system known as neuro-inflammaging. For example, glia excitation by cytokines and glia pro-inflammatory productions contribute significantly to memory injury as well as in acute systemic inflammation, which is associated with high levels of Tumor necrosis factor -α and a rise in cognitive decline. In recent years its role in the pathology of Alzheimer's disease has caught research interest to a large extent. This article reviews the connection concerning the immune and nervous systems and highlights how immunosenescence and inflamm-aging can affect neurodegenerative disorders.

Longevity, Centenarians and Modified Cellular Proteodynamics

We have shown before that at least one intracellular proteolytic system seems to be at least as abundant in the peripheral blood lymphocytes of centenarians as in the same cells of young individuals (with the cells of the elderly population showing a significant dip compared to both young and centenarian cohorts). Despite scarce published data, in this review, we tried to answer the question how do different types of cells of longevous people-nonagenarians to (semi)supercentenarians-maintain the quality and quantity of their structural and functional proteins? Specifically, we asked if more robust proteodynamics participate in longevity. We hypothesized that at least some factors controlling the maintenance of cellular proteomes in centenarians will remain at the "young" level (just performing better than in the average elderly). In our quest, we considered multiple aspects of cellular protein maintenance (proteodynamics), including the quality of transcribed DNA, its epigenetic changes, fidelity and quantitative features of transcription of both mRNA and noncoding RNAs, the process of translation, posttranslational modifications leading to maturation and functionalization of nascent proteins, and, finally, multiple facets of the process of elimination of misfolded, aggregated, and otherwise dysfunctional proteins (autophagy). We also included the status of mitochondria, especially production of ATP necessary for protein synthesis and maintenance. We found that with the exception of the latter and of chaperone function, practically all of the considered aspects did show better performance in centenarians than in the average elderly, and most of them approached the levels/activities seen in the cells of young individuals.

Aging affects responsiveness of peripheral blood mononuclear cells to immunosuppression of periodontal ligament stem cells

Objectives

The effect of age on the response of peripheral blood mononuclear cells (PBMCs) to immunosuppression induced by human periodontal ligament stem cells (hPDLSCs) is unclear. The identity of the cytokines most effective in inducing the PBMC immune response remains unknown. This study investigated the effects of age on immunophenotype, proliferation, activation, and cytokine secretion capacities of PBMCs following co-culture with hPDLSCs.

Methods

PBMCs were collected from younger (16–19 years) and older (45–55 years) donors, then co-cultured with confirmed hPDLSCs for various lengths of time. T lymphocyte proliferation and cell surface marker expression were analyzed by flow cytometry. Cytokine expression levels were measured by quantitative polymerase chain reaction assays and enzyme-linked immunosorbent assays.

Results

CD28 expression by T lymphocytes decreased with age, indicating reduced proliferation; CD95 expression increased with age, indicating enhanced apoptosis. Moreover, hPDLSCs inhibited T lymphocyte proliferation in both age groups; this inhibition was stronger in cells from older donors than in cells from younger donors. Age reduced the secretion of interleukin-2 and interferon-γ, whereas it increased the secretion of tumor necrosis factor-β by PBMCs cultured with hPDLSCs.

Conclusions

Aging may have a robust effect on the response of PBMCs towards hPDLSC-induced immunosuppression.

Impact of aging on calcium influx and potassium channel characteristics of T lymphocytes

Adaptive immunity and T cell function are affected by aging. Calcium influx patterns, regulated by Kv1.3 and IKCa1 potassium channels, influence T cell activation. We aimed to compare calcium influx kinetics in CD8, Th1 and Th2 cells in human peripheral blood samples obtained from five different age groups (cord blood, 10-15 ys, 25-40 ys, 45-55 ys, 60-75 ys).

We measured calcium influx using flow cytometry in samples treated with or without specific inhibitors of Kv1.3 and IKCa1 channels (MGTX and TRAM, respectively).

Calcium influx was higher in Th1 cells of adults, however, its extent decreased again with aging. Importantly, these changes were not detected in Th2 cells, where the pattern of calcium influx kinetics is similar throughout all investigated age groups. MGTX had a more pronounced inhibitory effect on calcium influx in Th2 cells, while in Th1 cells the same was true for TRAM in the 25-40 ys and 45-55 ys groups. Calcium influx of CD8 cells were inhibited to a similar extent by both applied inhibitors in these groups, and had no effect in the elderly.

Altered lymphocyte potassium channel inhibitory patterns, regulators of calcium influx kinetics, might contribute to the development of age-related changes of T cell function.

Immunosenescence and age-related viral diseases

Immunosenescence is described as a decline in the normal functioning of the immune system associated with physiologic ageing. Immunosenescence contributes to reduced efficacy to vaccination and increased susceptibility to infectious diseases in the elderly. Extensive studies of laboratory animal models of ageing or donor lymphocyte analysis have identified changes in immunity caused by the ageing process. Most of these studies have identified phenotypic and functional changes in innate and adaptive immunity. However, it is unclear which of these defects are critical for impaired immune defense against infection. This review describes the changes that occur in innate and adaptive immunity with ageing and some age-related viral diseases where defects in a key component of immunity contribute to the high mortality rate in mouse models of ageing.

Impact of age on T cell signaling: a general defect or specific alterations?

Decreased immune responsiveness associated with aging is generally termed "immunosenescence". Several theories have been proposed to explain age-related declines in immune responses. Here, we will focus on and describe potential defects in T cell signal transduction from the membrane to the nucleus, leading to changes in the type, intensity and duration of the response as a major factor contributing to immunosenescence. We will first detail T cell signaling through the T cell receptor (TCR), CD28 and IL-2 receptor (IL-2R) and then discuss the observed age-related alterations to these signaling pathways. The role of membrane rafts in T cell signaling and T cell aging will be described. These factors will be considered in the context of the notion that age-related changes to T cell signaling may be attributed to changes in the functionality of the T cells due to shifts in T cell subpopulations with age. For this reason, we conclude by highlighting the application of multiparametric signaling analysis in leukocyte subsets using flow cytometry as a means to obtain a clearer picture with respect to age-related changes to immune signaling.

Human innate immunosenescence: causes and consequences for immunity in old age

The past decade has seen an explosion in research focusing on innate immunity. Through a wide range of mechanisms including phagocytosis, intracellular killing and activation of proinflammatory or antiviral cytokine production, the cells of the innate immune system initiate and support adaptive immunity. The effects of aging on innate immune responses remain incompletely understood, particularly in humans. Here we review advances in the study of human immunosenescence in the diverse cells of the innate immune system, including neutrophils, monocytes, macrophages, natural killer and natural killer T (NKT) cells and dendritic cells-with a focus on consequences for the response to infection or vaccination in old age.

Renal transplantation: older recipients and donors

The majority of patients receiving a renal allograft, including a kidney from an older donor, do well. Renal transplantation from a living donor is associated with distinct advantages, including prolonged allograft survival. When live donors are not available, however, deceased donor kidneys provide suitable renal function that frequently lasts the lifetime of elderly recipients. Elderly patients who receive a kidney transplant enjoy improved survival, better quality of life, and lower medical costs than those who remain on dialysis.

Level of NK cytotoxic activity in the elderly aged more than 80 years

A group of healthy volunteers aged 60-93 years, was evaluated with respect to their NK activity. These people have been under careful medical observation for 3 years and were selected according to Senieur Protocol criteria. NK activity of each person was checked at least three times at regular 12-month intervals with the chromium release test and twice at the same interval of time with a single cell cytotoxicity assay. NK activity of 60-79-year-old females was in a similar range of values as that of young females (20-35 years) and was lower than that of the males of the corresponding age groups. The females aged 80-88 years revealed the highest NK activity. The chronically ill 80-88-year-old females, on the other hand, were characterized by a marked decrease of NK activity in relation to their age counterparts. NK activity of both the females and males significantly declined at the age of 89-93 years. The significance of NK activity for survival is discussed.

First autopsy study of an Okinawan centenarian: absence of many age-related diseases

Consistent with the compression-of-morbidity hypothesis, several studies have reported that a significant proportion of centenarians delay or escape age-related diseases. Of those who live with such diseases for a long time, many appear to do so with better functional status than do younger persons who do not achieve extreme old age. The authors describe the first autopsy in an Okinawan-Japanese centenarian who escaped many age-related illnesses and delayed frailty toward the end of her very long life. Her late-life morbidity pattern is contrasted with that of white centenarians.

The allergy epidemic extends beyond the past few decades

BACKGROUND

Increased prevalence of allergic diseases in western societies has been described as an epidemic. The precise turning point for the epidemic and the antigens responsible for it remain obscure.

OBJECTIVE

To evaluate how the prevalence of atopic disease has changed in terms of detectable sensitization to aeroallergens and dietary allergens in a cross-sectional comparison of subjects from birth cohorts more than 60 years apart.

METHODS

We studied four groups of 100 subjects each (at ages 7, 27, 47 and 67 years), representing those born in 1990, 1963-66, 1943-46 and in 1923-26, respectively. Serum total and specific IgE concentrations against aeroallergens and dietary allergens were determined. A questionnaire elicited information on symptoms, allergic diseases and medication.

RESULTS

The proportion of subjects with detectable IgE antibodies against aeroallergens increased consistently from the oldest to the youngest birth cohorts; chi2 trend=56.809, P<0.0001. Similar progression was not seen in sensitization to dietary allergens. The proportion of those with diagnosed asthma differed significantly (chi2=13.45, P=0.004) across the birth cohorts. The lowest prevalence of asthma and sensitization to dietary allergens was detected in those born in 1943-46, i.e. during or immediately after World War II.

CONCLUSION

Prevalence of sensitization to airborne allergens, unlike that to dietary allergens, has increased over a long period of time. Our results support the concept of the immune function being programmed by external factors early in life. They also call for caution when interpretations of the pace and possible causes of the allergy epidemic are made on the basis of short-term studies.

The effect of age and gender on cytokine production by human peripheral blood mononuclear cells and markers of bone metabolism

BACKGROUND

Aging has been associated with various alterations of immune functions, the musculoskeletal system and a decline of sex hormone levels. Estradiol has a central role in the regulation of bone turnover and also modulates the production of cytokines such as interleukin-1 and -6 and tumor necrosis factor-alpha. We therefore studied the effect of age and gender on cytokine production by mononuclear cells and markers of bone metabolism.

METHODS

Peripheral blood mononuclear cells were isolated from young and elderly subjects; intracellular detection of cytokine production after stimulation with ionomycine and PMA (T cells) or LPS (monocytes) was performed by four color flow cytometry. Sex hormone levels and markers of bone metabolism were measured by RIA or ELISA:

RESULTS

When we compared elderly to young women we found an increased proportion of T cells that were positive for interferon-gamma, interleukin-2, -4, -10 and -13. Also the percentage of cells producing interleukin-4 or interferon-gamma within the CD8(+) population was higher in the group of elderly women. In contrast, proportionally fewer monocytes of elderly women were positive for tumor necrosis factor-alpha or interleukin-6 than those of young women. In elderly men a higher percentage of T cells produced interleukin-2, -4 and -13. In the group of aged men we found a higher frequency of cells that produced interleukin-4 within the CD4(+) or CD8(+) population. Moreover, within monocytes of elderly men we found an increased percentage of cells positive for both interleukin-1beta and tumor necrosis factor-alpha. The data on markers of bone metabolism indicated an increase of bone turnover in old age.

CONCLUSION

Our data demonstrate that aging is associated with significant alterations of bone metabolism and cytokine production by T cells and monocytes. For particular cytokines (interferon-gamma and interleukin-10 in T cells, interleukin-6 and tumor necrosis factor-alpha in monocytes) these changes are gender specific.

Dietary intake and eating patterns of elderly people in Israel: who is at nutritional risk?

OBJECTIVE

To determine dietary intake and eating patterns of older persons in Israel and to identify factors associated with low intake.

DESIGN

A cross-sectional study.

SETTING

Community-dwelling participants living in the Beer-Sheva area were interviewed at home, using a 24 h food questionnaire with additional questions regarding health and eating habits. Dietary intake was compared between people aged 65-74 and 75 y and older.

SUBJECTS

A total of 377 people over the age of 65 224 aged 65-74 and 153>75, were randomly selected from the Negev population.

RESULTS

Dietary intake of energy, fat, carbohydrates, vitamins E, C and B(1) were significantly lower for people aged 75 and older compared with people aged 65-74. Low energy intake was associated with lower subjective health status for men (P<0.01), poor appetite (P<0.01) and more gastrointestinal problems (P<0.05) for women and lower snack consumption (P<0.01) for both genders. In a multivariate model, low energy intake was associated with low appetite and higher use of medication for both sexes and with frequency of eating alone and not consuming snacks for men.

CONCLUSIONS

Dietary intake is lower among individuals older than 75 than in 65-74 y old. Risk factors for low intake include poor appetite and health status, gastrointestinal problems, and eating alone. Snacking enhanced dietary intake and should be encouraged in this group.

T cell subset patterns that predict resistance to spontaneous lymphoma, mammary adenocarcinoma, and fibrosarcoma in mice

Aging leads to changes in the proportion of several T cell subsets in peripheral blood, but it is not yet known whether these changes have prognostic significance for late-life diseases. To examine this question, levels of T cell subsets were measured at 8 and 18 mo of age in the peripheral blood of mice of a genetically heterogeneous stock, and the mice were then subsequently evaluated for life span and for cause of death. The results indicate that mice whose T cell subset patterns look like those of old mice tend to die at earlier ages, regardless of the specific cause of death. At 18 mo, 39% of the variance within the set of seven measured subsets could be combined statistically into a single number, whose correlation with individual subsets suggested that it could be interpreted as an index of immunological aging. T cell subset pattern, as represented by this index, was a predictor of life span in mice dying of lymphoma, fibrosarcoma, mammary adenocarcinoma, or of all other causes considered together. Even as early as 8 mo of age, T cell subset patterns are significant predictors of all three forms of cancer, although at this age the association is stronger in mated female mice than in virgin mice. These results support two controversial hypotheses, which are not mutually exclusive: 1) early immune senescence might predispose to early death from cancer and 2) differences in aging rate, as monitored by tests of immune status, might accelerate or decelerate a wide range of late life neoplastic diseases.

Kidney transplantation in older patients: benefits and risks

The proportion of older patients accepted for dialysis is increasing every year both in the US and abroad. Of the two treatment modalities for end-stage renal disease, i.e. dialysis and transplantation, the latter offers more freedom and is associated with better clinical outcome. Most elderly patients seem to have excellent functional rehabilitation after a kidney transplant. However, in view of the wide gap between the availability of cadaver organs and the people in need, giving the precious organ to the elderly who have a shorter expected lifespan may present an ethical problem. Therefore, it has become increasingly important to offer the kidney to only those who have no significant comorbid conditions or other high risk factors, so as to improve the odds of success after renal transplantation.

Intrinsic and environmental influences on immune senescence in the aged monkey

Several factors associated with the age-related decline in immunity were examined in three studies on aged rhesus monkeys. Natural killer (NK) cell activity was found to be low in many monkeys after 20 years of age, but exceptionally long-lived animals, older than 25 years, often had vigorous cytolytic responses. When NK activity was decreased in an aged monkey, it was predictive of fewer years of survival and a younger age at death. This prediction of mortality was associated with one nonimmune biomarker of aging in the monkey: nail growth rate. Monkeys with very slow nail growth and low NK activity were likely to die sooner. Although these findings might suggest an immutable course for the aging process, the housing conditions of old monkeys also had a pronounced effect on their NK activity. The highest NK responses were found in old monkeys housed with just one other old animal when compared to living alone or with just a young, juvenile monkey. It remains to be determined whether this type of psychosocial influence could have a sustained effect on immunity and ultimately change the pace of aging and time to mortality.

Immunogenetics of longevity. Is major histocompatibility complex polymorphism relevant to the control of human longevity? A review of literature data

Literature data suggest that human longevity may be directly correlated with optimal functioning of the immune system. Therefore, it is likely that one of the genetic determinants of longevity resides in those polymorphisms for the immune system genes that regulate immune responses. Accordingly, studies performed on mice have suggested that the Major Histocompatibility Complex (MHC), known to control a variety of immune functions, is associated with the life span of the strains. In the last 25 years, a fair number of cross-sectional studies that searched for the role of HLA (the human MHC) genes on human longevity by comparing HLA antigen frequencies between groups of young and elderly persons have been published, but conflicting findings have been obtained. In fact, the same HLA antigens are increased in some studies, decreased in others and unchanged in others. On the whole, that could lead us to hypothesize that the observed age-related differences in the frequency of HLA antigens are due to bias. In our opinion, this hypothesis is real for most studies owing to major methodological problems. However, some studies that do not meet these biases have shown an association between longevity and some HLA-DR alleles or HLA-B8,DR3 haplotype, known to be involved in the antigen non-specific control of immune response. Thus, HLA studies in man may be interpreted to support suggestions derived from the studies on congenic mice on MHC effects on longevity. However, in mice the association may be by way of susceptibility to lymphomas whereas, in human beings, the effect on longevity is likely, via infectious disease susceptibility. Longevity is associated with positive or negative selection of alleles (or haplotypes) that respectively confer resistance or susceptibility to disease(s), via peptide presentation or via antigen non-specific control of the immune response.

HLA, aging, and longevity: a critical reappraisal

Despite a large number of studies, available data do not allow at present to reach definitive and clear conclusions on role of HLA on longevity, owing to major methodological problems, such as serological and molecular typing of different loci, insufficient sample sizes, different inclusion criteria and age cut-off, inappropriate mixing of data referred to people from 58 to over 100 years of age, inappropriate control matching, and neglected consideration of sex-related effects and the different genetic make-up of studied populations. However, within this confused scenario, some data emerge. First, two studies that do not fit the biases above discussed show that some HLA alleles are associated with longevity. However, some of these alleles may confer an increased risk to undergo a variety of diseases. Second, longevity may be associated with an increased homozygosity at HLA loci. Third, an intriguing association between longevity and the 8.1 ancestral haplotype (AH), which has been proven to be associated with a variety of immune dysfunctions and autoimmune diseases, apparently emerges. This association appears to be a sex-specific (males) longevity contributor, and it is particularly interesting, taking into account that a type 2 (early infancy) --> type 1 (adulthood) --> type 2 (aging) shift of cytokine profile occurs lifelong, and that individuals bearing this haplotype show a type 2 immune responsiveness (note that type 1 cytokines mainly enhance cellular responses, whereas type 2 cytokines predominantly enhance humoral responses). On the whole, the (sex specific) association of longevity with alleles or haplotypes of several genes related to risk factors for a variety of diseases (cardiovascular diseases, cancer), including HLA alleles and haplotypes, is not unexpected on the basis of previous studies on the genetics of longevity in centenarians. This association can be interpreted under the perspective of a well known evolutionary theory of aging (antagonistic pleiotropy). This theory predicts that the same gene (or allele or haplotype) can have different roles (positive or negative) in different periods of the life span. Thus, the 8.1 AH should exert a positive effect during the infancy and aging but not in adulthood, when, indeed it is associated to susceptibility to a variety of diseases.

beta-Carotene and selenium supplementation enhances immune response in aged humans

Background: Nutritional research has focused on the effects of specific nutrients' ability to cause or prevent cancer. While beta-carotene and selenium (both important for antioxidant systems) have cancer prevention capabilities, their antineoplastic mechanism(s) remains to be elucidated. Methods: In a prospective, randomized study design we evaluated immunological changes in free-living, healthy aged humans (57-84 years of age) given a placebo, beta-carotene (45 mg/day), and/or selenium (400 µg/day) supplement for 6 months and after 2 months of discontinuation. Peripheral blood lymphocytes were evaluated and subtyped using flowcytometry. Natural killer (NK) cell cytotoxicity was determined by a fluorescent method. Plasma diene conjugates were assessed to evaluate changes in oxidative stress. Results: Selenium and selenium plus beta-carotene supplementation caused an increase in total T cells by 27% and 31%, respectively (p <.05). The only group that was different (in T lymphocytes) from the controls (placebo group) after 6 months of supplementation (p <.05) was the selenium-supplemented group (+65%). Much of this increase was the result of an increase in CD4(+) T-cell subsets. Selenium or beta-carotene supplementation for 3 months increased NK cell cytotoxicity over pretreatment levels by 58% and 34%, respectively; however, these levels returned to +12% and -6% of pretreatment levels after 6 months supplementation. Selenium plus beta-carotene supplementation caused an increase in the percentage of NK cell by 121% and 161% at 3 and 6 months, respectively. However, the increased numbers of NK cells were not correlated with NK cell activity. Conclusions: We found that selenium enhanced immune function (NK cell cytotoxicity) and phenotypic expression of T-cell subsets, whereas beta-carotene affected only immune function. Increased NK cell cytotoxicity may last for only a short period of supplementation and was not sustained throughout the 6 months of supplementation. Supplemental selenium and beta-carotene seemed to affect immune function in aged subjects by different mechanisms.

Changes with age in the modulation of natural killer activity of murine leukocytes by gastrin-releasing peptide, neuropeptide Y and sulfated cholecystokinin octapeptide

Several investigations have suggested that the interactions between the nervous and immune systems are modified with age. The aim of the present work was to study the effect of three neuropeptides: gastrin-releasing peptide (GRP), neuropeptide Y (NPY) and sulfated cholecystokinin octapeptide (CCK-8 s) on natural killer (NK) activity of spleen, thymus and axillary node leukocytes from BALB/c male, young (8+/-1 weeks), adult (24+/-2 weeks) and old (72+/-2 weeks) mice. We used cells from murine lymphoma YAC-1 as targets for the cytotoxic assay and three physiological concentrations of the neuropeptides (10(-8), 10(-10) and 10(-12) M). In control samples, in the absence of neuropeptide, we observed a decreased NK activity in young and old mice with respect to the adults in the three organs studied. Regarding the effect of the neuropeptides, GRP stimulates the cytotoxic activity of leukocytes from all locations, in adult animals. At the same age, NPY also stimulates the NK activity of leukocytes from axillary nodes and thymus, whereas it decreases the NK activity of spleen leukocytes from young mice. CCK-8 s has an inhibitory effect on the axillary node leukocytes from young mice and spleen leukocytes from old animals. However, CCK-8 s increased the NK activity of thymus leukocytes from young and adult mice. The results indicate that the highest values of NK activity are found in adult mice, and that the stimulating effect of the three neuropeptides studied on NK activity of leukocytes from adult mice are reduced or disappeared, in general, in old as well as in young animals. Furthermore, the changes observed with ageing in the modulation of NK activity by the neuropeptides studied suggest an altered integration of the nervous and immune systems.

CD28 expression in T cell aging and human longevity

Functional decrements of the immune system have a major contribution to aging and age-related diseases. Here, we further characterize the decline in proportion of CD28-positive T cells previously identified in centenarians. Cohorts of 97 centenarians, 40 subjects aged 70-90 (ELD group), and 40 young adults (under age 40) were phenotyped for T cell surface expression of CD28, CD4, and CD8 antigens. The significant decline in T cells expressing CD28 (p < 10(-4) for comparisons between adults and either ELD or centenarians) affects preferentially the CD8+ subset of T cells. This decline accounts largely for the age-related diminution of T cell responsiveness to mitogenic signals. CD28 expression is modulated in T cell cultures in a growth-related fashion and this modulation is dampened in cultures from centenarians. We propose that the decrease in CD28 expression reflects a compensatory adaptation of the immune system during aging in the face of chronic stimulation.

Increased natural killer cell cytotoxicity in Alzheimer's disease may involve protein kinase C dysregulation

Increased cytokine-mediated cytotoxic natural killer (NK) cell activity has recently been demonstrated in patients with senile dementia of the Alzheimer's type (SDAT). In the present study, we evaluated whether protein-kinase C (PKC), a main regulatory enzyme involved in the mechanism of exocytosis by NK cells, has a role in the cytotoxic response of NK cells (during IL-2 and IFN-beta exposure) from SDAT patients. Our data demonstrate the presence of an increased cytotoxic response by NK cells to IL-2 (mean increase +102%) and IFN-beta (mean increase +132%) in SDAT patients in comparison with healthy elderly subjects (+75% and +88% for IL-2 and IFN-beta, respectively). A smaller suppression of NK cytotoxicity after cortisol was also observed in SDAT (mean decrease -24%) than in the control group (-44%). The NK cell activity of SDAT patients was inversely correlated with the cognitive status as evaluated by the analysis of MMSE (Mini Mental State Examination) score. A comparison of young and elderly healthy subjects revealed no variations in NK cell activity. A physiological decrease in cytosolic PKC activity was demonstrated in healthy old subjects after IL-2 and IFN-beta incubation, but not in SDAT patients, while no variations in kinase activity were observed after cortisol incubation. The decreased activity with cytokines was associated with reduced levels of PKC alpha and betaII isoforms. An alteration in cytokine-mediated NK cell activity associated with PKC dysregulation is therefore suggested to occur in patients with SDAT. These changes may indicate the existence of an immunological component to the pathogenesis and progression of the disease.

Relationship between routine hematological parameters, serum IL-3, IL-6 and erythropoietin and mild anemia and degree of function in the elderly

To investigate the influence of functioning on unexplained senile anemia, we measured commonly used hematological parameters (serum iron, transferrin, iron saturation and ferritin) in addition to specific erythropoietic factors, such as interleukin-3 (IL-3), interleukin-6 (IL-6), and erythropoietin (EPO) in 48 elderly subjects aged 65-90 years. The subjects were divided into 3 groups: 1) 17 patients with unexplained mild anemia; 2) 17 non-anemic patients with newly acquired stroke and who previously were functionally active; 3) 14 functionally active patients with no major disease who served as controls. Anemia was defined as hemoglobin (Hb) values under 12.0 g/dL. The degree of functional ability was defined and scored by the "functional independence measure" (FIM) test. Data are presented as mean values +/- SD. The results revealed a correlation between the functional state and levels of Hb, iron and transferrin with unchanged iron saturation. Patients in the mild anemia group were found to be functionally declined (FIM = 57 +/- 19.4) with the relatively lowest mean iron (75.1 +/- 17 micrograms/dL) and transferrin levels (243 +/- 42.6 micrograms/dL). The stroke group (FIM = 62 +/- 17.7) had intermediate levels of iron (85.4 +/- 20.3 micrograms/dL) and transferrin (245 +/- 45.2), and with the continuation of the declined functional state the Hb level decreased significantly (13.7 +/- 0.9 to 12.0 +/- 1.0 g/dL, p < 0.001). The highest mean values of iron (102 +/- 27.9 micrograms/dL) and transferrin (322 +/- 42.7 micrograms/dL) were found in the control group (FIM = 122.7 +/- 5.8). The ferritin levels showed an opposite trend. IL-3 values were undetectable in the anemic and control groups, and were elevated in some patients in the stroke group. The lowest IL-6 level was observed in the anemic group, and the highest in the control group. Serial IL-6 assays in the stroke group showed an upward trend. Erythropoietin levels in all groups showed no difference.

Genetics of aging

The role of genetics in determining life-span is complex and paradoxical. Although the heritability of life-span is relatively minor, some genetic variants significantly modify senescence of mammals and invertebrates, with both positive and negative impacts on age-related disorders and life-spans. In certain examples, the gene variants alter metabolic pathways, which could thereby mediate interactions with nutritional and other environmental factors that influence life-span. Given the relatively minor effect and variable penetrance of genetic risk factors that appear to affect survival and health at advanced ages, life-style and other environmental influences may profoundly modify outcomes of aging.

Physiological basis for long life span

A collection of clinical data is reported on nonagenarians in comparison to an 'average' population of younger age. The results of these clinical data indicated that a vital physiological basis for long life span probably existed. The basis include a better micro-blood-flow state, a better cardiac, immune (nature killer cell activity), adrenocortical, hepatic and renal function, and a higher level of high density lipoprotein cholesterol. It is suggested that the method, including Chinese traditional medicine, to improve the micro-blood-flow, nature killer cell activity, high density lipoprotein cholesterol and vital organ function may be beneficial for life preservation and aging retarding.

HLA and longevity or aging among Shanghai Chinese

Twenty-two centenarians and one hundred and seventy-nine nonagenarians (mean age 93 +/- 1.04 years) in the Shanghai Region of China were phenotyped for alleles of A (13 types), B (21 types) and C (6 types) loci of the human leukocyte antigen (HLA). The frequencies of HLA antigens were compared with 211 healthy adults whose ages ranged from 20 to 50 years. It was observed that A9 was highly associated with longevity (frequency in the longevity group is 38%, the control group 24%, P = 0.002). A30 showed marked inverse correlation (frequency in the longevity group is 8%, the control group 17%, P = 0.008). Cw3, Cw6 and Cw7 were also inversely correlated (P = 0.02, 0.04 and 0.02, respectively). Thus, it is likely that A9 may contribute to longevity while A30, Cw3, Cw6 and Cw7 may be associated with aging. The average superoxide dismutase (SOD) contents of erythrocytes in 48 cases with the HLA-A9 (without A30) antigen in the longevity group and in 13 cases with the HLA-A30 (without A9) antigen in the control group were 555 +/- 96 and 593 +/- 58 micrograms/gHb, respectively (t = 1.375, P > 0.05).

Prevalence of organ-specific and non organ-specific autoantibodies in healthy centenarians

In the present study we have investigated the prevalence of organ-specific and non organ-specific autoantibodies in 26 healthy centenarians (6 men, 20 women; age range 101-106 years), using as controls 54 healthy old (33 men and 21 women, age range 71-93) and 56 young subjects (29 men and 27 women, age range 26-60). We assayed sera of each group for the following organ-specific autoantibodies, anti-gastric mucosa (anti-PCA), anti-thyroglobulin (anti-Tg) and non organ-specific autoantibodies, anti-cardiolipin (anti-APA IgG and IgM), anti-nuclear antigens (anti-ANA), anti-double strand DNA (anti-ds-DNA), anti-extractable nuclear antigens (anti-ENA). Finally, natural anti-alpha-galactosyl (anti-alpha-GAL) antibodies were also analyzed. As expected, in the old subjects there was a significant increase of prevalence of anti-Tg and anti-PCA autoantibodies. By contrast, in centenarians the prevalence of organ specific anti-Tg and anti-PCA antibodies was not significantly different from that observed in controls aged less than 60 years. The prevalence of non organ-specific autoantibodies anti-APA (IgG), anti-APA (IgM), anti-ANA, was significantly increased both in the elderly and centenarians when compared with the prevalence observed in sera from the young. Anti-ENA and anti-dsDNA antibodies were not detected in all groups studied. Finally, the prevalence of natural anti-alpha-GAL antibodies significantly increases with age, including centenarians. In conclusion, we confirm and extend the results previously obtained by other authors. In fact, as already described, the prevalence of organ-specific autoantibodies in the elderly is not seen after the tenth decade of life. Interestingly, the prevalence of non organ-specific autoantibodies is instead increased in these subjects, suggesting that different mechanisms are involved in the pathogenesis of these autoantibodies. Particularly, these autoantibodies could be the expression of a damaged tissue process rather than of an autoimmune one, as suggested by data concerning natural antibodies.

A shift to Th0 cytokine production by CD4+ cells in human longevity: studies on two healthy centenarians

Centenarians, particularly healthy centenarians, constitute the example of successful aging and the study of their immune status can help to define the endpoint of the changes occurring throughout life. We characterized T cell clones (TCC) of two healthy centenarians, studying their phenotypes and production of representative Th1 and Th2 cytokines (IFN-gamma and IL-4) and compared them with TCC obtained by three young normal subjects; in all 180TCC were analyzed. In young donors, 35TCC were CD4+, 56CD8+ and 2 were alpha beta +CD4-CD8- (double negative). In centenarians, we obtained 46CD4+TCC, 38CD8+, 2CD4+CD8+ (double positive) and 1 gamma delta + double negative. Of the young subjects' TCC, 71% produced IFN-gamma but no IL-4 (Th1 pattern) and this prevalence decreased to 39% in TCC from the centenarians. The number of clones showing the opposite Th2 pattern was similar in young and aged donors (3 out of 93TCC and 2 out of 87TCC, respectively). The intermediate profile of TCC producing both IL-4 and IFN-gamma (Th0) was found in 25.8% of clones from young people, but it almost doubled to 58.6% in centenarians. The analysis shows that the Th profiles of CD8+TCC is nearly superimposable in the two groups, whereas a major shift from a Th1 to a Th0 pattern is presented by CD4+TCC. The balance provided by a majority of CD4+TCC showing a Th0 pattern may ensure both humoral and cell-mediated defences. In CD8+TCC, however, a Th1 pattern still is present, possibly for efficient generation of cytotoxic responses. These findings should be extended by studying other centenarians and elderly subjects.

Humoral immunity in aging

The interactions between B and T lymphocytes, leading to the development of humoral responses, are reviewed with references to the changes occurring in aged people. Aging is perceived as a process of impairment of immune functions; it is known that T cells from aged subjects have a reduced ability to produce IL-2. However, other functions seem to be upregulated in elderly subjects; indeed, IL-1, IL-3, IL-4, IL-6 and TNF alpha production are increased both in aged mice and humans. These cytokines are known to control B cell differentiation, through isotype switch and Ig production. A significant increase in IgG subclasses and IgA is observed in sera of aged subjects. This contrasts with the significant decrease in circulating B lymphocytes. The impairment of primary responses to immunization, and other aspects of humoral immunity, including mucosal responses, autoantibody production and correlations with phenotypic markers of T and B cell subsets, are discussed.

Renal replacement therapies in the elderly: Part II. Renal transplantation

The United States end-stage renal disease (ESRD) population is growing progressively older. As a percentage of the overall ESRD population, the number of patients 65 years of age and older approached 40% by 1989. However, the percentage of ESRD patients with a functioning transplant was only 2.7% in this age group. Success of transplantation in geriatric ESRD patients over the last decade is due to improved patient selection as well as the use of cyclosporine A and lower doses of corticosteroids, with the achievement of 1-year patient and graft survival rates of 85% and 75%, respectively. For patients older than 60 or 65 years, the 5-year "functional" graft survival is 55% to 60%. Although overall results are excellent, the management of transplantation in the elderly requires an understanding of pharmacology, immunology, and physiology peculiar to this age group. Since the elderly have a degree of immune incompetence, they require less aggressive immunotherapy. Elderly patients have decreased hepatic enzyme activity, especially the P450 system, and therefore require a lower cyclosporine dose. Although elderly patients experience less rejection episodes than younger patients, graft loss in the elderly transplant recipient is due mainly to patient death. Most common causes of death in the elderly transplant recipient are cardiovascular disease and infection related to peaks of immunosuppression. Shortage of cadaver kidneys and limited life expectancy of the geriatric ESRD patient make allocation of cadaver kidneys to patients over 70 years (and even 65 years) a controversial issue and an ethical dilemma. Use of elderly cadaver donors (over 55 to 60 years) is associated with inferior success rates and is not an optimal solution to shortage of cadaver kidneys.

Analysis of peripheral blood lymphocyte cell surface density of functional and activation associated markers in young and old hemodialysis patients

Aging has been associated with specific shifts in various peripheral blood immune competent cell subsets. As part of pre-transplant immune profile evaluation possible parallel age-related changes in mean T-cell surface density of several cluster differentiation and activation linked antigens were into 2 groups: group 1-114 patients 40 years old or younger and group 2-36 patients 55 years old or older. Peripheral blood CD3+, DR+, CD3+DR+, CD4+, CD4+DR+, CD8+, CD8+DR+, CD56+, CD8+CD56+, CD3+IL-2-R+ and CD3+TR+ (interleukin-2 and transferrin receptors bearing CD3+ cells respectively), all mononuclear cells expressing IL-2-R and TR, and CD4+CD45+ cell subsets were analyzed and enumerated by 2-color flow cytometry. Subset relative levels as well as absolute counts were recorded. Cell surface density computation was performed using a computerized mathematical model based on fluorescence intensity vector analysis and cell size score determination based on light scatter pattern from raw data obtained by flow cytometry studies. Younger age was significantly associated with higher absolute cell count of CD3+ (p < 0.001), DR+ (p < 0.05), CD4+ (p < 0.01), CD8+ (p < 0.005), CD3+IL-2-R+ (p < 0.05), CD3+TR+ (p < 0.03) and IL-2-R+ (p < 0.05). Older patients had a slightly higher mean absolute count of CD4+CD45+ subset (p not significant) and significantly higher mean count for CD8+CD56+ cell subset (p < 0.001). When cell subset levels were compared between the 2 groups as the relative fraction of cells expressing a given marker out of all mononuclear cells gated out by flow cytometry, younger age was significantly associated with higher levels of CD3+ (p < 0.005), CD8+ (p < 0.001), CD4+DR+ (p < 0.004), CD3-TR+ (p < 0.05) and CD8+IL-2-R+ (p < 0.05). In contrast, slightly higher subset levels of CD56+ (p not significant), and significantly elevated levels of CD8+CD56+ (p < 0.0019) and CD4+CD45+ (p < 0.004) were observed in the older patients. Cell surface density analysis showed that younger patients had higher mean density per cell of CD3 (p < 0.05), CD8 (p < 0.001), IL-2-R on CD3+ cells (p < 0.05) and TR on CD3+ cells (p < 0.05). Mean cell surface density of CD56 on all CD56+ cells as well as on CD8+ cells was higher in older individuals (p < 0.001 and p < 0.003, respectively).(ABSTRACT TRUNCATED AT 400 WORDS)

Age related increase in the intra-alveolar macrophage population of non-smokers

The alveolar macrophage population is higher in smokers than in non-smokers. An age related increase in the alveolar macrophage number in the lungs of non-smokers has been found, whether expressed per unit lung volume or per unit lung surface area.

Changes in circulating B cells and immunoglobulin classes and subclasses in a healthy aged population

The study of 87 adults of different ages, including 15 centenarians, selected for their healthy status, showed that profound changes of humoral immunity occur throughout life. In particular, a statistically significant age-related increase of the serum level of immunoglobulin classes (IgG and IgA but not IgM) and IgG subclasses (IgG1, 2 and 3, but not IgG4) was detected. A parallel age-related decrease of circulating B cells was also observed. The hypothesis of a complex derangement of B cell function and/or compartmentalization with age is put forward, together with the proposal that healthy centenarians (as representative of successful ageing) may be helpful in identifying the physiological age-related modifications of the immune system.

Longevity and heredity in humans. Association with the human leucocyte antigen phenotype

Several arguments support the idea of a link between longevity and heredity, both in experimental animals and in the human species. In mice, genes in the major histocompatibility complex (MHC) are associated with a significant effect on life span. Results of analogous studies in man are confusing and contradictory. We have therefore investigated the question of an association of the human leucocyte antigen (HLA) and longevity in a large and ethnically homogeneous population. Our study population consisted of all 964 available inhabitants aged 85 years and over in the Dutch community of Leiden (pop. 104,000). Our control group comprised 2444 young inhabitants, aged 20-35 years, with an identical ethnic and demographic background. In addition, control groups of different age-brackets from the same region were used. Two antigens differed in frequency: HLA-B40 was lower and HLA-DR5 was higher in the group of 85 years and over, as compared to the control group, aged 20-35 years. Both differences were more evident in females. No major disease associations with HLA-B40 or HLA-DR5 have been reported. It is unlikely that these results are a chance observation: the overall similarity of the HLA pattern of the old and young age groups is a confirmation of their identical ethnic and demographic background and the changes as observed in the different age-groups were gradual. The biological meaning of these results is still unclear.

Aging and immune function

Since it is too difficult to study aging of the organism as a whole, most investigators try to focus on a specific physiological system that exhibits age-dependent functional changes, in the hopes that elucidation (in biochemical and developmental terms) of the mechanism of senescent change will provide insight into the aging process itself. The immune system is among the most maleable of such models, in that well-defined cell types will produce well-defined molecules with predictable functions in vitro and in vivo. The increasing power of basic immunological science should, in the next decade, permit an increasingly fine appreciation of how aging leads to immune decline. This expanding conceptual framework will then suggest new ideas about the role of immunosenescence in degenerative, infectious, and neoplastic illnesses and may also generate increasingly rational strategies for therapeutic intervention.

Leukocyte immunophenotyping by flow cytometry in a multisite study: standardization, quality control, and normal values in the Transfusion Safety Study. The Transfusion Safety Study Group

The Transfusion Safety Study (TSS) is a multicenter, cooperative investigation of factors that may determine the occurrence and modify the expression of transfusion-transmitted infections. A flow cytometry laboratory was established in each of the six participating centers in order to avoid alterations in cell phenotypes which may be caused by shipping delays, temperature changes, and handling. As a consequence, in order to assure compatibility of results, stringent standardization, quality control, and proficiency testing procedures were developed. This paper documents (i) the effect of time from phlebotomy to specimen staining and then to analysis for the antibodies used in the study; (ii) the effects of variations in light scatter cursor location for certain antibodies; (iii) a quality control program and data management and analysis system, each specifically designed for the study; and (iv) presents extensive data on age- and sex-related reference (normal) ranges for the several individual and paired monoclonal antibodies used in the study. Problems encountered, including obtaining reliable absolute lymphocyte counts, interference by nucleated erythrocytes, and sources of variability in results, are discussed. This study is meant to serve as a reference for future TSS publications.

The role of T cell phenotypes in decreased lymphoproliferation of the elderly

A possible mechanism of the decreased mitogen-induced lymphoproliferation of the elderly is a shift in the relative numbers of T lymphocyte subpopulations. Results from studies examining such changes have been conflicting. In an effort to resolve this conflict, alterations in T cell subsets in the peripheral blood of a large number of relatively healthy, elderly subjects (149; mean age 84.6) were evaluated. Although there were several differences in percentages of subpopulations between elderly and young subjects, no significant differences in the absolute numbers of lymphocytes, monocytes, or T cell subsets between the groups were observed. In addition, there was no correlation between mitogen-induced lymphoproliferation and T cell subsets. Since the decreased mitogen response could reflect a difference in the ability of one T cell subset to proliferate, the phenotype of the T cells after stimulation with PHA was determined. Although the elderly demonstrated a decreased number of all T cell subsets after PHA stimulation compared to young subjects, the most pronounced decrease was in CD8+ cells. Further, young individuals demonstrated a significant increase in the percentage of CD8+ cells (p less than 0.001) after 72 hr of culture with PHA; elderly subjects showed no change in the percentage of T cell subsets. Although both groups had an increase in interleukin 2 receptor (IL2R), transferrin receptor (TfR), and MHC class II Ag (HLA-DR) positive cells after PHA stimulation, the mean percentage of TfR+ cells was significantly greater in the young than in the elderly (p less than 0.05). This decreased expression of TfR+ cells in the elderly was reflected by a decreased percentage of CD8+ cells expressing TfR. In addition, the percentages of CD8+ cells, CD8+ cells expressing TfR, and CD8+ cells expressing IL2R after activation correlated with PHA-induced proliferation. These results suggest that the impaired lymphoproliferative ability of elderly cells is not related to the proportions of T cell subsets present in peripheral blood. Rather, there appears to be some defect in the ability of all T cells, but especially of the T suppressor/cytotoxic cells, of the elderly to respond to PHA manifested by a decreased expression of transferrin receptors.

The potency-sparing radical cystectomy: does it compromise the completeness of the cancer resection?

Anatomical radical cystectomies with en bloc pelvic lymph node dissections were performed post mortem on 10 male cadavers. The traditional technique of radical cystectomy was used on 1 side and the potency-sparing technique was used on the opposite side. The tissue responsible for the differences in the surgical margins with the 2 procedures was examined by routine surgical pathological techniques to determine if it contained lymph nodes. Lymph nodes were identified in the bundle of tissue left in the pelvis with the nerve-sparing radical cystectomy in 6 of the 10 dissections (60 per cent). Because these lymph nodes may represent the potential first site of metastatic disease leaving the bladder, the reader is cautioned about adopting the nerve-sparing radical cystectomy as part of the management of invasive bladder cancer until the long-term sequelae of the procedure are known.

Age-related changes in human lymphocyte subsets: progressive reduction of the CD4 CD45R (suppressor inducer) population

The purpose of this study was to investigate, by double-labeling immunofluorescence, lymphocyte subsets in the peripheral blood of healthy children, adults, and aged individuals. The absolute number of T and B lymphocytes decreases with age. The decline in T cells was attributed to a decrease in CD4 lymphocytes. We also found that the composition of the CD4 subset changes with age: in children the CD45R molecule is expressed on the majority of CD4 cells, whereas in aged subjects the absolute number of these lymphocytes is greatly reduced. The reciprocal CD4 CD29 population is not modified during the life span. Aging is also associated with the appearance of CD8 Leu 7 lymphocytes. Putative contrasuppressor cells, identified by Vicia villosa binding, represent a very small population in peripheral blood and are not subject to age-dependent variations.

Influenza vaccination in the elderly: improved antibody response with Imuthiol (Na diethyldithiocarbamate) adjuvant therapy

To improve influenza vaccine efficacy in hospitalized elderly, we compared the evolution of antibody level after vaccination in three patient groups. A sample of apparently primo vaccinated elderly were randomized to receive either Imuthiol (Na diethyldithiocarbamate: group 1) or a placebo (group P). They were compared to patients who had been vaccinated annually for several years (group C). All patients were immunized in the same week. Antibody responses increase within 15 days to reach a plateau in group P and C, while they continue to increase in the Imuthiol treated group, reaching higher antibody levels 30 days after vaccination. This higher antibody rise in group I is essentially due to higher antibody responses in patients with initially low antibody levels and who exhibited at least a four-fold antibody rise. This effect of Imuthiol on influenza antibody responses was observed in spite of a lower nutritional status in this group, a condition that induces lower antibody responses. The higher antibody responses observed in the Imuthiol treated group allow longer protection against influenza.