UP-REGULATION OF HIGH-AFFINITY DEHYDROEPIANDROSTERONE BINDING-ACTIVITY BY DEHYDROEPIANDROSTERONE IN ACTIVATED HUMAN T-LYMPHOCYTES

Although evidence indicates that dehydroepiandrosterone (DHEA) exerts direct physiological effects, its mechanism of action remains unknown. DHEA binding sites were examined using a whole-cell binding assay in a human T lymphoid cell line, PEER, revealing that a single class of h igh-affinity binding sites for DHEA (dissociation constant = 7.4 +/- 0 .53 nmol/L, mean +/- SE, n = 4) was greatly increased when treated wit h DHEA, phorbol-12-myristate-13-acetate, and the Ca2+ ionophore A23187 . Bound[H-3]DHEA was displaced sensitively by DHEA and secondarily by dihydrotestosterone but not effectively by other steroids, including D HEA sulfate. These results not only indicate the existence of a DHEA r eceptor, but also suggest that T cells become susceptible to regulatio n by DHEA during the process of signal-induced activation.