Interleukin-8 concentrations are elevated in peritoneal fluid of women with endometriosis

OBJECTIVE: To investigate the presence of interleukin-8 (IL-8), a macrophage-derived angiogenic factor, in peritoneal fluid (PF) of women with and without endometriosis. DESIGN: Case-control study. SETTING: University hospital. PATIENTS: Eighteen women with laparoscopic findings of mild to severe endometriosis, and nine women with no visual evidence of pelvic pathology. MAIN OUTCOME MEASURES: Peritoneal fluid IL-8 levels were determined using an ELISA. Interleukin-8 concentrations were compared among women with and without endometriosis. Correlation between PF IL-8 concentration and endometriosis stage was investigated. RESULTS: Interleukin-8 was detectable in the PF of a majority of women (67%). Interleukin-8 concentrations were higher in the PF of women with endometriosis than in matched normal controls. A significant correlation between PF IL-8 concentration and endometriosis stage was noted. CONCLUSIONS: We hypothesize that IL-8 is an important angiogenic factor that contributes to the pathogenesis of endometriosis by promoting the neovascularization of ectopic endometrial implants.