No abstract

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.

No abstract

Incubation of human monocytes, derived from peripheral blood, with cell-free supernatants from mixed lymphocyte cultures resulted in morphological and functional changes in the mature macrophages. Activation of monocyte-derived macrophages by these factors resulted in a significant increase in their capacity to lyse anti-D-treated human erythrocytes. The lytic activity of both normal and activated macrophages appeared to be independent of erythrophagocytosis. T lymphocytes activated by either allogeneic cells or the mitogen phytohaemagglutinin were not cytolytic to treated erythrocytes even at high effector to target cell ratios.

No abstract