Peritoneal fluid concentrations of interleukin-8 in patients with endometriosis depend on the severity of the disorder and are higher in the luteal phase.

Background: Previous evaluations of the relationship between the concentrations of interleukin-8 (IL-8) in the peritoneal fluid and endometriosis led to non-consistent results. Our purpose was to investigate the correlation of the concentrations of IL-8 in the peritoneal fluid with the stage of endometriosis, the presence of red lesions and the phase of the menstrual cycle.

Methods: Ninety-two patients with infertility (n = 87) or undergoing sterilization (n = 5) had peritoneal fluid samples collected at laparoscopy. IL-8 determinations were performed using an enzyme-linked immunosorbent assay.

Results: The concentrations of IL-8 in the peritoneal fluid of the 68 women with endometriosis were not significantly different from those of the 24 controls. Patients with moderate/severe stages had IL-8 significantly higher than controls (P = 0.008) and marginally higher than patients with minimal/mild endometriosis (P = 0.053). Concentrations of IL-8 were significantly higher in patients than in controls in the luteal phase. Red lesions were associated with significantly increased levels of peritoneal fluid IL-8 only in the luteal phase.

Conclusions: Our findings reinforce the importance of IL-8 in the pathogenesis of endometriosis.