Opposing effects of methylprednisolone on in vitro alloantigen-induced cytotoxic and suppressor lymphocytes in man.

The effects of the steroid methylprednisolone (MP) on the induction of cytotoxic or suppressive lymphocytes in human mixed lymphocyte cultures (MLC) have been examined. Concentrations of MP sufficient to inhibit both the cellular proliferation and the generation of cytotoxic lymphocytes in MLC appeared to have very little effect on the induction of suppressor cells in these cultures. In fact, over a certain dosage range of MP an increased number of suppressor cells appeared to be generated. Moreover, low concentrations of MP greatly potentiated the effects of alloantigen induced suppressor cells but had little or no effect on the action of cytotoxic lymphocytes as measured in the cell mediated lympholysis assay. It seems therefore that MP has an opposing effect both on the generation and function of suppressor or cytotoxic lymphocytes induced by allogeneic cells.