Mechanisms of corticosteroid action on lymphocyte subpopulations: VI. Lack of correlation between glucocorticosteroid receptors and the differential effects of glucocorticosteroids on T-cell subpopulations

Glucocorticosteroid receptors were measured in subpopulations of human peripheral blood T cells identified by the presence of an Fc receptor for IgG (T_G) or an Fc receptor for IgM (T_M). T_M cells are selectively depleted from the circulation by in vivo administration of glucocorticosteroids as opposed to T_G cells which are relatively resistant to the lymphodepletive effects of these hormones. However, this selective lymphodepletive effect of glucocorticosteroids on T_M cells could not be explained on the basis of detectable differences in intracytoplasmic glucocorticosteroid receptors in these T-cell subpopulations since T_G and T_M cells had quantitatively similar glucocorticosteroid receptors as well as remarkably similar dexamethasone binding affinities and dissociation constants. Hence, the strikingly different effects of glucocorticosteroids on the circulatory kinetics of T_G and T_M cells must be explained by mechanisms other than those at the level of the glucocorticosteroid receptor.