Inhibition of in vitro lymphokine synthesis by glucocorticosteroids

At pharmacological levels, glucocorticosteroids inhibited two antigen-induced lymphocyte functions, in vitro proliferation and lymphokine synthesis. Lymphocyte production of both macrophage chemotactic factor (CTX) and macrophage inhibition factor (MIF) were decreased in the presence of hydrocortisone. The corticosteroid also blocked the action of MIF on macrophages but did not interfere with the action of CTX on macrophages. Thus, steroids can suppress the immune response at two different stages: by blocking lymphocyte activation and mediator synthesis and also by interfering with the interaction of certain effector molecules with their target cells. Furthermore, these findings suggested that MIF and CTX have distinct mechanisms of action on the effector macrophages, one being sensitive and one resistant to steroids.