Abstract

T cell suppressor function in patients with systemic lupus erythematosus (SLE) was evaluated by studying the ability of concanavalin A- (Con A) activated T cells to suppress proliferative responses by responder cells autologous with the Con A-activated T cells. Impaired suppressor T-cell activity in patients with SLE was observed with regard to three effector functions: 1) the allogeneic response of T cells, 2) the Con A response of T cells, and 3) the B cell response to pokeweed mitogen (PWM). No defect was found with regard to suppression of the T-cell response to phytohemagglutinin (PHA). Mixing experiments between SLE and normal cells were carried out to further define the nature of the SLE suppressor defect. When responder cells from SLE patients were cultured with Con A-activated T cells from normal controls, the normal suppressor T cells caused suppression of SLE responder cells. In contrast, Con A-activated T cells from SLE patients were incapable of exerting suppressor effects on normal responder cells. These observations indicate that the impaired suppressor activity in SLE patients resides in the generation of suppressor T cells, rather than in the response to suppressor T cell signals.