Differential effects of glucocorticosteroids on the functions of helper and suppressor T lymphocytes.

The effects of dexamethasone (Dex) on the functions of antigen-primed helper and suppressor T cells were studied in humoral immune responses in vitro. In doses equivalent to elevated physiologic concentrations, the suppressor T cell activity was abolished. In contrast, the helper T cell function was resistant to even pharmacologic concentrations of Dex. The apparent steroid resistance of the helper T cells was found to be mediated by the products of activated macrophages. While macrophage factors protected helper T cells from steroid inhibition, they did not prevent the effects of Dex on suppressor T cells. Because bacterial cell wall and membrane components are potent inducers of the factors that mediate steroid resistance of helper T cells, the combination of physiologically elevated levels of steroids and macrophage factors during acute infections may function to facilitate the expression of host immunity. However, the persistance of these conditions, as in chronic inflammation, may also contribute to the pathogenesis of autoimmunity by perturbing the balance of immune regulation by helper and suppressor T cells.