Changes in suppressor, helper, and B-cell functions in aging mice

Suppressor, T-helper, and B-cell functions were measured in spleen cells derived from individual mice of varying ages. Suppressor activity was assessed by the ability of test cells to suppress the secondary anti-hapten response of young-adult spleen cells in mixed cultures. T-Helper-cell activity was assessed by measuring the ability of T cells activated with carrier-anti-carrier immune complexes to restore the response of hapten-primed, T-depleted syngeneic cells. B-Cell activity was assessed by measuring the response to the T-independent antigen DNP-Ficoll. It was found that the suppressor function increased rapidly, reached a peak in middle-aged mice, and remained elevated thereafter. In contrast, T-helper and B-cell functions declined at a constant rate from young adulthood to old age. An exception to this pattern was found in a distinct subpopulation of aged mice, which had splenomegaly and extremely low suppressor, T-helper, and B-cell functions.