The differential effects of hydrocortisone on activation and tolerance induction in human T lymphocyte clones

Abstract

The in vitro effects of hydrocortisone on T cell activation and tolerance induction were investigated using human influenza virus immune T cell lines and clones. Hydrocortisone at 10 −9 to 10 −6 molar concentrations was able to inhibit the antigen induced but not the T cell growth factor (TCGF) mediated proliferative response of both the lines and clones. However, hydrocortisone was able to inhibit TCGF production by cloned T cells. The proliferative response of cloned T cells to intact influenza virus A/Texas/1/77 was more markedly inhibited by equivalent concentrations of hydrocortisone than was the response of that clone to a 24 amino acid sequence (p20) of the haemagglutinin molecule implying that hydrocortisone may also act at the level of antigen processing. Furthermore hydrocortisone was able neither to induce T cell tolerance alone nor to inhibit antigen specific tolerance induction. However, hydrocortisone did lower the antigen threshold for tolerance induction. The possible mechanisms of hydrocortisone activity in the modulation of T cell regulation in autoimmune disease are discussed.