The effect of hydrocortisone (HC) on sodium periodate and phytohemagglutinin-induced [3H]thymidine incorporation and lymphokine production by human lymphocytes.

Hydrocortisone (HC) in pharmacologically attainable concentrations was shown to inhibit mitogen-induced lymphocyte blastogenesis. When adherent and nonadherent cells were treated separately with hydrocortisone and then reconstituted, treatment of either cell population resulted in a diminished mitogen-activated response. HC-treated adherent cells produced less interleukin 1 (IL-1) than control cells, and interleukin 2 (IL-2) production by HC-treated lymphocytes was also reduced. This latter finding could not be reversed by adding IL-1-containing adherent cell supernatants to the culture systems. Leukocyte inhibiting factor (LIF) production by sodium periodate-activated mononuclear cells was also reduced after HC treatment, but could be corrected by adding IL-1-containing adherent cell supernatants to the cultures. PHA-induced LIF production, which is less dependent upon adherent cells and their products, was not affected by HC treatment. It is concluded that HC exerts its suppressive effect by independently inhibiting IL-1 production by adherent cells and IL-2 production by lymphocytes.