SECRETION OF TUMOR-NECROSIS-FACTOR-ALPHA BY TESTICULAR MACROPHAGES

While it has been shown that culture medium from testicular macrophages can influence testosterone production when added to Leydig cells, the identity of the factor(s) responsible for this activity remains unknown. Since tumor necrosis factor alpha (TNFalpha) has been shown to be capable of influencing testosterone production by Leydig cells, a series of studies was conducted to determine if testicular macrophages produce TNFalpha. It was found that testicular macrophages from adult rats produce a factor that is capable of lysing L929 cells, which are used as a traditional bioassay for TNFalpha. The TNFalpha activity in the macrophage-conditioned medium could be neutralized by the addition of anti-murine TNFalpha but not with the addition of preimmune IgG. While lipopolysaccharide (LPS) slightly increased the release of TNFalpha, neither follicle-stimulating hormone (FSH) nor testosterone had a similar effect. It was not determined if the isolation procedure had artificially 'activated' the macrophages. Medium from cultured Sertoli cells, Leydig cells and peritubular cells did not contain TNFalpha activity. These studies are consistent with the hypothesis that the paracrine interaction between testicular macrophages and Leydig cells is mediated in part by TNFalpha.