B cell immunosenescence in the elderly and in centenarians.

The elderly suffer from an increased susceptibility to infectious disease and cancer. Aging of the immune system contributes to this state of affairs due to immunosenescence. Because repeated intermittent or chronic antigen exposure may lead to lymphocyte clonal exhaustion, chronic antigenic stress plays a part in the compromised immunity of the elderly, who have accumulated a lifetime's exposure to infectious agents, autoantigens, and cancer antigens. Literature on immunosenescence has focused mainly on T cell impairment, but B cell compartment is also affected. The age-dependent B cell changes documented by the present review indicate that advanced age per se is a condition characterized by lack of B clonotypic immune response to new extracellular pathogens. In any event, data are suggesting that the loss of naive B cells could represent a hallmark of immunosenescence and could provide a biomarker possibly related to the life span of humans and potentially useful for the evaluation of anti-aging treatment. Since information on the senescence of B cells is of obvious interest, further studies are necessary to confirm these suggestions as well as to extend the number of markers used to characterize the cells.