The role of activated accessory cells in preventing immunosuppression by hydrocortisone.

The generation of humoral immunity in vitro by normal and antigen-primed mouse spleen cells was suppressed by in vitro treatment with hydrocortisone. Functions of normal and antigen-activated helper T lymphocytes and of accessory cells were inhibited by the corticosteroids. Spleen cells cultured overnight in medium containing fetal bovine serum became highly resistant to the effects of hydrocortisone. Similar resistance was found to occur when spleen cells were cultured with accessory cells that previously had been activated with bacterial lipopolysaccharide. These studies show that immunologically nonspecific processes significantly alter the effects of the steroids on specific immune responses and suggest that accessory cell products modulate T cells in ways which differ from antigen induction.