Inhibitory effect of 11 beta-hydroxypregna-1,4-diene-3,20-dione (delta HOP) on lymphocyte proliferation.

We have compared the immunosuppressive effect of delta HOP and glucocorticoids on lymphocyte proliferation and IL-1 secretion. The new synthetic steroid only inhibited proliferation of phytohaemagglutinin (PHA)-stimulated human lymphocyte at high concentrations and the effect did not persist after washing out the steroid. In contrast, glucocorticoids produced the classical dose-response inhibition and the effect persisted when they were removed from the cultured medium. Although both steroids decreased IL-1 secretion from human monocytes stimulated with lipopolysaccharide (LPS), they exert the same effect through a different mechanism. The experiments we report suggest that the decrease of IL-1 synthesis produced by delta HOP could be caused by inhibition of LPS phagocytosis. These results support our hypothesis that delta HOP exerts its immunosuppressive and anti-inflammatory effect by a non-genomic mechanism.