Heterogeneity of human suppressor cells induced by concanavalin A as determined in simultaneous assays of immune function.

Abstract

Abstract Incubation of normal human peripheral blood mononuclear cells with mitogenic doses of concanavalin A (Con A) resulted in the generation of a population of cells that could simultaneously suppress mitogen- or alloantigen-induced lymphoproliferation as measured by the incorporation of 3H-thymidine and pokeweed mitogen (PWM)-induced polyclonal immunoglobulin production as measured by a reverse hemolytic plaque assay. Treatment of the cells with mitomycin C after Con A activation did not alter their ability to mediate suppression in either of the assays. The cell or cells responsible for suppression of proliferation or immunoglobulin production by freshly added autologous or allogeneic responders were present in a T cell-enriched population, but not in non-T cell or monocyte fractions. Treatment of the T cell population before Con A activation with an antiserum from a systemic lupus erythematosus patient that demonstrated selective anti-T cell activity resulted in the inability to generate suppressor activity in the mixed leukocyte reaction (MLR) and a statistically significant, but partial defect in the ability to generate suppressor cells for PWM-induced polyclonal immunoglobulin production. Further, this treatment had no effect on the generation of suppressor cells for proliferative responses induced by phytohemagglutinin (PHA) or PWM. Finally fractionation of T cells by rosetting with antibody-coated ox erythrocytes revealed that only Fc (IgG)+ T cells (Tγ) functioned as precursors of suppressors for the MLR, whereas both Fc (IgG)+ T cells (Tγ) and Fc (IgG)- T cells (Tnon-γ) could be activated to suppress PHA-induced proliferation and PWM-induced polyclonal immunoglobulin production.