DIFFERENTIAL-EFFECTS OF RECOMBINANT INTERLEUKIN-1-ALPHA AND INTERLEUKIN-1-BETA ON LEYDIG-CELL FUNCTION

Previously we have reported that human chorionic gonadotropin(hCG)-stimulated testosterone biosynthesis was markedly inhibited by purified natural human interleukin-1(IL-1). In the present study we evaluated the effects of human and murine recombinant IL-1 (rIL-1) on Leydig cell steroidogenesis in primary culture. Human rIL-1β caused a dose-dependent inhibition of hCG-, 8-bromo cyclic AMP-, and forskolin-induced testosterone formation. In contrast, human rIL-1α was considerably less potent. When the effects of the cytokines were corrected for their biological potencies, human rIL-1 β and murine rIL-1α were still more effective than human rIL-1α in inhibiting testosterone production (at least 100-fold more potent). Thus, even though IL-1α and IL-1β bind to the same receptors on T cells, Leydig cells exhibit differential sensitivity in response to rIL-1α and rIL-1β which is partly species dependent. © 1990.