Corticosteroids in human lymphocyte-mediated cytotoxic reactions: effects on the kinetics of sensitization and on the cytolytic capacity of effector lymphocytes in vitro.

The present experiments tested the ability of hydrocortisone and methylprednisolone to alter the process of in vitro generation of cytotoxic T lymphocytes against specific alloantigens or to suppress the lytic phase of the subsequent cytotoxic reactions. The continuous presence of hydrocortisone in culture reduced the total number of cytotoxic lymphocytes recovered following their sensitization in mixed leukocyte cultures. However, corticosteroids had no direct effect on the processes required for generation of cytotoxic lymphocytes, since equal numbers of effector lymphocytes generated in the presence or absence of hydrocortisone produced equivalent, specific lympholysis. The addition of either hydrocortisone or methylprednisolone only during the cytolytic phase of cell-mediated lympholysis failed to significantly suppress the killing of lymphocyte targets. In contrast, parallel studies of the capacity of the same lymphocytes to serve as effector cells in antibody-dependent cellular cytotoxicity showed that both hydrocortisone and methylprednisolone directly inhibited the killing of Chang liver cells sensitized with low concentrations of antibody.