Elevated interleukin-6 levels in peritoneal fluid of patients with pelvic pathology

Objective: To determine if interleukin 6 (IL-6) is a normal constituent of peritoneal fluid (PF), and if various types of pelvic pathology influence its presence within the PF microenvironment. Study Design: Peritoneal fluid from 73 women obtained at the time of laparoscopy was examined for the presence of IL-6 using an IL-6 specific sandwich enzyme-linked immunosorbent assay. Thirty-nine patients had pelvic endometriosis, 17 had nonendometriotic pelvic adhesive disease, and 17 subjects undergoing tubal sterilization without evidence of pelvic pathology served as controls. Results: Immunoreactive IL-6 was observed in the PF of all 73 subjects (range 0.26 to 11.16 ng/mL). The mean concentration of IL-6 was higher in women with nonendometriotic pelvic adhesions as compared with control subjects (1.28 ± 0.16 versus 0.80 ± 0.06 ng/mL, P < 0.03). There was no difference in the mean peritoneal concentrations of IL-6 between women with endometriosis (1.16 ± 0.28 ng/mL) and controls, P = 0.38. Twenty-seven of 73 patients (37%) demonstrated elevated levels (>1.0 ng/mL) of IL-6. Patients with pelvic adhesions were significantly more likely to have elevated concentrations of IL-6 than controls (10/17 [59%] versus 3/17 [18%], P < 0.02). Alternatively, the percentage of patients with elevated IL-6 concentrations did not differ between patients with endometriosis or controls (14/39 [36%] versus 3/17 [18%], P > 0.10). Conclusions: These findings demonstrate that IL-6 is a normal constituent of PF and that elevated levels are found in many patients with pelvic adhesions.