Inhibition of in vitro immunosuppressive effects of glucocorticosteroids by a competitive antagonist RU-486.

The 19-nor-steroid RU-486 is an antagonist of glucocorticosteroids acting competitively at the receptor level. Pharmacological and endocrinological studies have already shown that RU-486 is able to reverse glucocorticosteroid effects. The present study shows that RU-486 can counteract the inhibitory effect of glucocorticosteroids in two highly corticoid-sensitive in vitro immune responses: murine in vitro antibody response and human autologous mixed lymphocyte reaction.