Colony formation by subpopulations of T lymphocytes. IV. Inhibitory effect of hydrocortisone on human and murine T cell subsets.

The sensitivity of human T lymphocyte colony formation to hydrocortisone (HCS) was studied in the presence and absence of an exogenous source of interleukin-2(IL-2). In the presence of IL-2, T colony formation by T inducer/helper (Th) cells was found to be 100-fold more resistant to the inhibitory effect of HCS in vitro than colony formation by T suppressor/cytotoxic (Tsc) cells, the IC50 values for HCS being 10(-4)M and 10(-6)M, respectively. In the absence of IL-2,Tsc cells do not form colonies and T cell colony formation by Th cells is inhibited 50% by less than 5 x 10(-8)M HCS. T lymphocyte colony formation by murine cortical thymocytes in vitro was inhibited by physiological concentrations of HCS in vitro, the IC50 value being 2 x 10(-8)M HCS. T cell colony formation by medullary thymocytes and peripheral lymphocytes was found to be 100-fold more resistant to HCS than control cells, the IC50 value being 2 x 10(-6)M HCS.