Immunity and age: living in the past?
Increasing age is associated with a decreasing ability to mediate effective immune responses to newly encountered antigens. It is generally believed that this reflects the age-associated decline in the number, repertoire and function of available naive T cells. Here, we propose that naive T cells become increasingly irrelevant to the immune system, and that responses to newly encountered antigens are progressively dominated by cross-reactive memory T cells as the individual ages. In addition, we propose that the majority, if not all, of the response to newly encountered antigens in the elderly is mediated by cross-reactive memory T cells. This predicts highly stochastic responses to new infections that should vary between individuals, and has important implications for vaccination strategies in the elderly.
Woodland
David L
DL
Trudeau Institute, Saranac Lake, NY 12983, USA. dwoodland@trudeauinstitute.org
Blackman
Marcia A
MA
D000368:Aged; D000369:Aged, 80 and over; D000375:Aging / Q000276:immunology*; D000818:Animals; D006801:Humans; D007156:Immunologic Memory; D013601:T-Lymphocytes / Q000276:immunology*