Effects of methylprednisolone on the in vitro induction and function of suppressor cells in man.

The effects of the steroid methylprednisolone on the induction of suppressor lymphocytes in human mixed lymphocyte cultures (MLC) have been examined. Concentrations of methylprednisolone (MP) sufficient to inhibit both the cellular proliferation and the generation of cytotoxic lymphocytes in MLC appeared to enhance the induction of suppressor cells in these cultures. Maximum enhancement of suppressor cell induction occurred at an MP concentration of approximately 1 microgram/ml. Moreover, the presence of low concentrations of methylprednisolone, not sufficient to inhibit proliferation in MLC, significantly potentiated the inhibiting effect of suppressor cells on cellular proliferation. The inhibition observed by the combined effect of MP and suppressor cells was equivalent to that seen using five times as many suppressor cells alone.