en Physiology Physiology Original Research: Basic Science in Medicine Original Research: Basic Science in Medicine One of the mechanisms involved in the regulation of the immune system by steroid hormones could be the monocytic-macrophage system. In this study the effect of the male hormone 5a-DHT on cytokine release by peritoneal macrophages (mΦ) of male and female NZB/BALBc mice was investigated. Macrophages from male mice activated with LPS produced a greater amount of IL-1β (21.8%) (p<0.05) and IL-6 (19.3% ) (p<0.0 1) than age-matched females. However, the total amount of TNF-α released by LPS-activated macrophages was greater (24.8%) (p<0.05) in female than male mice. 5α -DHT enhanced IL-1β and reduced IL-6 release by activated macrophages in a dose-dependent fashion. The effect of 5aD HT on TNF-α release was not exactly dose-dependent Therefore, it is likely that the modulation of the immune system by steroid hormone may partly be due to the effect of 5α -DHT on the secretion of cytokines by the monocytic-macrophage system. Macrophage, Sex hormone, 5α-DHT, Cytokine. 223 228 http://mjiri.iums.ac.ir/browse.php?a_code=A-10-1-355&slc_lang=en&sid=1 KAZEM AHMADI-RENANI 20031947532846005097 20031947532846005097 Yes From the Department of Immunology, Faculty of Medicine Baghiatollah University of Medical Sciences, Tehran, Islamic Republic of Iran ALAN B. McCRUDEN 20031947532846005098 20031947532846005098 No the Department of Immunology, University of Strathclyde, Glasgow, G4 ONR, U.K.