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, exhibi t longer life span and lower lymphoma incidence than do mice selected for low responses. The link between immunity and aging is further evid enced by the age-related alterations of the immune system, mostly of t he T-cell population, in terms of replacement of virgin by memory cell s, accumulation of cells with signal transduction defects, and changes in the profile of Th1 and Th2 type cytokines. Also, B cells exhibit i ntrinsic 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 possi ble cytokine interventions to prevent or treat age-related immune diso rders, as they may affect the duration and the biological quality of l ife.