Differential effects of glucocorticosteroids on the functions of subpopulations of helper T lymphocytes.

The in vitro effects of dexamethasone on the activities of Th1 and Th2 helper cell subpopulations were examined in secondary (IgG) responses to hapten-carrier conjugates under conditions where the selective or dominant expression of their individual activities could be observed. In the induction of IgG anti-hapten responses, carrier-primed Th1 cells cooperate with hapten-primed B cells by linked recognition of antigen, while carrier-primed Th2 cells cooperate with hapten-specific B cells by unlinked recognition of antigen. The function of carrier-primed Th1 cells was resistant to inactivation by dexamethasone. In contrast, the function of carrier-primed Th2 cells was abolished in the presence of pharmacologic concentrations of the steroid. The differential effects of dexamethosone on the activities of the two subpopulations of helper T cells could not be attributed to selective inhibition of a subpopulation of B cells which cooperate with Th2 cells.