The immune S ystem in the elderly

Abstract

Profound and complex changes in the immune response occur during the aging process. Immunosenescence is reflected by a sum of disregulations of the immune system and its interaction with other systems. Many of the changes would appear to implicate age-related deficiencies of the immune responses. The term immunosenescence designates therefore a sort of deterioration of the immune function which is believed to manifest itself in the increased susceptibility to cancer, autoimmune disease, and infectious disease. Evidence has been accumulating from several studies which suggest an association between immune function and individual longevity. However, there are observations, especially in very old healthy people, that several immune functions are unexpectedly well preserved and substantially comparable to those observed in young subjects. These findings raise the question of whether the alterations that can be observed in the immune parameters of the elderly are a cause or a result of underlying disease processes. Moreover, studies on centenarians revealed a remodeling of the immune system rather than a deterioration, suggesting that the changes observed during immunosenescence do not correspond to immunodeficiency. The underlying mechanisms of these events are however still unclear. The purpose of the present review is to assess the status of research on the immunobiology of aging. In this first section, we focus attention on the B cell biology of aging. In clinical practice, the changes in humoral immune responsiveness and antibody-mediated defense mechanisms could greatly influence the incidence and outcome of bacterial infections and autoimmune diseases as well as the response to vaccines.

Does aging affect the immune status? A comparative analysis in 300 healthy volunteers from France, Austria and Spain

“…In our well-defined healthy population, we found serum IgA levels were correlated with age, which is in agreement with other studies [27] and suggests either a complex derangement of B cell function with age [50] or a remodelling of the immune system rather than a deterioration [51]. Comparison between age groups showed that IgA levels were higher in subjects above 40 y.…”

Effect of age and frequency of injections on immune response to hepatitis B vaccination in drug users

“…An accelerating decline in immune responses to vaccination appears to manifest after 40 years of age, with less than 90% of vaccinees gaining protection, and the proportion drops precipitously to 65-75% at 60 years of age [27]. It is recognized that immune function generally declines in healthy elderly individuals, irrespective of underlying disease or environmental exposures [28, 29]. The shift toward humoral immune dysfunction is evident in lowered seroconversion rates and geometric antibody concentrations in elderly populations [25].…”

A high density of tertiary lymphoid structure B cells in lung tumors is associated with increased CD4+T cell receptor repertoire clonality

“…2 As humans age, immune responses become impaired, characterized by (1) reduced lymphopoiesis of new na€ ıve B and T cells, with novel BCRs 6 and TCRs, 7 respectively, (2) reduced dendritic cell (DC) function resulting in poor responses to inflammatory signals and lowered capacity to present antigen and to activate adaptive immune responses, 8 (3) poor germinal center formation, site of B cell expansion and selection, 9 and (4) decreased potential for T cell expansion, expression of activation markers, production of cytokines, diversity of TCR repertoire and delayed T cell responses to antigen. 7,10 Thus, these changes during aging help to explain the increased susceptibility to infection and reduced response to vaccinations in the elderly population.…”