Sexual dimorphism in phagocytic activity of wall lizard's splenic macrophage and its control by sex steroids

The splenic macrophages of wall lizards exhibited marked sex-related differ ence in their phagocytic activity. The percentage phagocytosis and phagocyt ic index in females was considerably higher than that of males. Gonadectomy resulted in significant increase in percentage phagocytosis and phagocytic index in both male as well as female lizards, suggesting that gonadal horm ones inhibit macrophage phagocytosis. This was further confirmed by dose an d time-related in vivo and in vitro experiments in which DHT suppressed pha gocytosis which increased with dose or duration of treatment, while E-2 eit her suppressed or had no effect on phagocytosis, depending on dose and dura tion of treatment. Exposure of macrophages to steroid receptor antagonists, cyproterone acetate (CPA), or tamoxifen citrate (Tam) prior to treatment w ith their respective sex steroids markedly reduced the DHT- or E-2-modulate d suppression of macrophage phagocytosis: It is concluded that the sex ster oids modulate splenic macrophage phagocytosis via receptor-mediated systems . (C) 1999 Academic Press.