Interleukin-1: a possible role in the infertility associated with endometriosis

Increased numbers of activated macrophages are associated with mild endometriosis. Interleukin-1 (IL-1) is a protein produced by macrophages and is believed to be a primary mediator of host responses. IL-1 induces prostaglandin and fibrinogen synthesis and stimulates fibroblast proliferation. This study was undertaken to evaluate the role of IL-1 in the infertility associated with mild endometriosis. Peritoneal fluid (PF) was obtained at laparoscopy from 11 patients with minimal or mild endometriosis and from 7 women undergoing tubal ligation. Peritoneal macrophages were isolated and cultured for 24 hours. Peritoneal and macrophage culture fluids were studied for IL-1 activity, which was measured with the EL-4 assay. IL-1 activity was present in the PF of 10 of the 11 patients with endometriosis and 11 of the 11 macrophage culture fluids and was absent in the PF and macrophage culture fluid of the tubal ligation patients. The effect of recombinant alpha-IL-1 on the in vitro growth of 2-cell mouse embryos was also studied. IL-1 in concentrations similar to those present in the PF (greater than 1 U/ml) was toxic to mouse embryo development. We conclude that the IL-1 may play a role in the infertility associated with endometriosis.