Suppression of DNA synthesis by con A-activated human lymphocytes: role of monocytes in con A-induced suppression

Human peripheral blood mononuclear leucocytes, activated by Con A, suppress the antigen- or mitogen-induced proliferation of autologous responder cells. Generation of suppressor cells is prevented by mitomycin treatment before Con A activation. Once cells are activated, their suppressive activity is not affected by mitomycin treatment. Monocytes are not only required for generation of suppressor cells, but are also involved in suppression as effector cells. Monocyte-mediated suppression is blocked by indomethacin, suggesting that this suppression is mediated by prostaglandin. It is concluded that monocytes are involved in Con A-induced suppression of DNA synthesis.