Sperm Phagocytosis by Human Peritoneal Macrophages

Pelvic endometriosis is associated with infertility even in women with few peritoneal implants, who ovulate, and have anatomically patent oviducts. Since peritoneal fluid is in contact with peritoneal endometrial implants as well as with the microenvironment in which fertilization occurs, it has the potential to influence fertilization adversely. The volume of peritoneal fluid in women of reproductive age varies with the menstrual cycle and is increased in women with endometriosis. This fluid contains variable numbers of leukocytes, of which more than 85 per cent are mononuclear phagocytes (macrophages). Because peritoneal macrophages have access to the reproductive tract via the oviducts, the authors of the present report conjectured that these cells might inhibit fertilization by injuring gametes. Women in the study were divided into three groups: (I) multiparous women (N = 10) who underwent laparoscopic tubal cauterization for sterilization or tubal rean-astomosis for reversal of previous sterilization; (II) infertile women (N = 12) without endometriosis; and (III) infertile women (N = 10) with endometriosis, who underwent diagnostic laparoscopy or therapeutic laparotomy. Peritoneal fluid from these patients was subjected to a sperm phagocytosis assay in vitro. The peritoneal fluid cells from all patients were predominantly macrophages, with few lymphocytes and only rare polymorphonuclear leukocytes. The cells displayed abundant cytoplasm, numerous lysosomes, phagocytic capability for antibody opsonized erythrocytes and latex particles, and nonspecific esterase positivity. Morphologically, macrophages from patients of the different groups did not appear to be different in size, vacuolization, or staining characteristics. Fertile patients (group I) had fewer total peritoneal macrophages (2.6 ± 0.7 × 106; mean ± SE) than did infertile patients without endometriosis (group II) (8.1 ± 2.7 × 106; P < 0.002) or infertile patients with endometriosis (group III) (18.2 ± 4.2 × 106; P < 0.002). Macrophages from group III were significantly more numerous than those from group II (P < 0.02). The phagocytosis assay actually measures both macrophage sperm phagocytosis and adherence to the mac-rophage surface. By light and transmission electron microscopy, the bulk was observed to be phagocytosis and not adherence to macrophages. No nonspecific adherence of sperm to the plastic was noted in control sperm chambers with macrophages and sperm. Macrophages from infertile patients with endometriosis (group III) had higher sperm phagocytosis than did those from infertile women without endometriosis in group II (primarily women with adnexal adhesions and tubal obstruction) (P < 0.002).