Human suppressor lymphocytes. II. Changes in concanavalin A inducible suppressor cells with age.

Suppressor cells were induced in peripheral blood mononuclear cells from young and old individuals by two day culture with Concanavalin A (Con A). Suppressor activity was quantitated using an alloantigen driven cytotoxicity assay. The proliferative responses of lymphocytes from young and old individuals to Con A and alloantigens were also determined. Results demonstrated that the numbers of Con A inducible suppressor cells were markedly decreased but equivalent proliferative responses to Con A were reduced compared to young individuals but equivalent proliferative responses to alloantigens were noted. Even though not statistically significant, alloantigen-induced cytotoxic responses were slightly increased in older persons. The increased alloantigen-induced cytotoxic responses of individuals noted in the present study may be related to the decreased numbers of suppressor cells in this group.