Immunoregulatory cells in aging mice. I. Concanavalin a-induced and naturally occurring suppressor cells

The status of concanavalin A (Con A)-triggered suppressor cells in aging mice was assessed in relation to untreated cells. Spleen cells of (C3H/ebJ×C57BL/6J)F₁ and (BALB/cJ × C57BL/6J)F₁ aging (20-41 months' old) and young (2-3 months' old) mice were triggered with Con A and examined for their capacity to suppress lymphocyte proliferative responses elicited by mitogens (Con A and phytohemagglutinin), by mixed lymphocyte reactions or by human gamma-globulin. Con A-triggered cells of the aged mice were found to be less efficient suppressors than those of the young, yet the aging mouse spleen cells exerted a more potent suppressive effect than the young, a priori, without pretreatment. Hence, the immune system in aging is characterized by a change in suppressor cell types; the Con A-triggered suppressors diminish and the naturally occurring, untreated ones become abundant.