The Effect of Hydrocortisone on the Production of γ-Interferon and Other Lymphokines by Human Peripheral Blood Mononuclear Cells

Concentrations of hydrocortisone as low as 0.08 μ/ml significantly reduced the yields of γ-interferon (IFN-γ) when phytohemagglutinin (PHA) or concanavalin A (ConA) were used as inducers; however, when staphylococcal enterotoxin A was utilized, higher concentrations (5.0 μg/ml) were required to achieve the same effect. Yields of interleukin-2 (IL-2) and lymphotoxin were also found to be sensitive to the effects of the steroids, but expressions of TAC antigen was not generally affected by these agents. In contrast to the effects of steroids on cell proliferation, lymphokine production remained suppressed after steroid withdrawal. Hydrocortisone appeared to influence the concentrations of cyclic nucleotides following lectin stimulation, but attempts to correct these alterations or to add exogenous IL-2 failed to restore lymphokine production to normal levels. Addition of the calcium ionophore A23187 partially restored IFN-γ production. We conclude that the effects of corticosteroids on the yields of lymphokines, including IFN-γ, are profound. The depression of lymphokine production appears to be associated with a number of alterations in the cell, including depression of protein synthesis, alterations in cyclic nucleotides, and diminution of the production of cofactors necessary for IFN-γ production. Enhancement of the flux of calcium into the cell may restore some of the ability to produce IFN-γ.