Peritoneal macrophages from patients with endometriosis release growth factor activity in vitro

We studied the in vitro secretion of macrophage-derived growth factor (MDGF) activity by peritoneal macrophages from fertile and infertile women. Peritoneal fluid was obtained from 55 women undergoing laparoscopy for evaluation and treatment of infertility or for tubal sterilization. Isolated macrophages were plated in tissue culture wells and incubated in Dulbecco's Modified Eagle's Medium plus 0.2% lactalbumin hydrolyzate at 37 C for 24 h. Medium MDGF activity was assayed by determining the ability of medium to stimulate [3H] thymidine incorporation in BALB-c 3T3 fibroblasts. Macrophages from 23 women released significant MDGF activity in vitro; the release was linear for up to 72 h. Among the 55 women, macrophages from 10 of 36 (28%) women with normal pelvic anatomy or tubal occlusion/pelvic adhesions released significant MDGF activity. In contrast, macrophages from 13 of 19 (68%) women with endometriosis, a significantly higher proportion (P less than 0.02), released MDGF. The finding that endometriosis is associated with in vivo primed peritoneal macrophages that produce MDGF in vitro may help to explain the proliferation or maintenance of endometrial tissue in the peritoneal cavity.