Expression of monocyte chemoattractant protein-1 in peritoneal endometriotic cells

It is well known that the number of peritoneal macrophages is increased in patients with pelvic endometriosis. We measured the concentration of monocy te chemoattractant protein-1 (MCP-1) using an enzyme-linked immunosorbent a ssay (ELISA) in the peritoneal fluid of women with and without endometriosi s. The expression of MCP-1 in pelvic endometriotic lesions obtained from th e peritoneum was also examined using immunohistochemistry and nonradioactiv e in situ hybridization. The mean concentration of MCP-1 in the peritoneal fluid was significantly higher in the patients with endometriosis (P<0.05). The most significant elevation, compared with non-endometriosis patients, was found in stage I of the disease (P<0.05). However, no statistically sig nificant difference was found among endometriosis stages I, II, III, and IV . Immunohistochemical staining revealed that MCP-1-positive cells were loca lized in the glandular epithelium of the endometriotic lesions and in the s tromal macrophages distributed in those lesions, but normal peritoneal cell s were negative. The in situ hybridization method demonstrated expression o f MCP-1 mRNA on the endometriotic glandular epithelium and stromal macropha ges. These findings suggest that MCP-1 may be involved in the histogenesis and early development of peritoneal endometriosis.