Genes, immunity, and senescence: looking for a link

Aging is under the control of a small number of regulatory genes. Mice genetically selected for high immune responses, in most cases, exhibit longer life span and lower lymphoma incidence than do mice selected for low responses. The link between immunity and aging is further evidenced by the age-related alterations of the immune system, mostly of the T-cell population, in terms of replacement of virgin by memory cells, accumulation of cells with signal transduction defects, and changes in the profile of Th1 and Th2 type cytokines. Also, B cells exhibit intrinsic defects, and natural killer (NK) cell activity is profoundly depressed by aging. In vitro experiments indicate that IL-2, IFN-gamma, and IL-4 production by mouse spleen cells changes with aging and may be upregulated by recombinant cytokines. These findings suggest possible cytokine interventions to prevent or treat age-related immune disorders, as they may affect the duration and the biological quality of life.