Analysis of cytokines in the peritoneal fluid of endometriosis patients as a function of the menstrual cycle stage using the Bio-Plex® platform

Objective: Endometriosis is a painful disease affecting 10-15% of reproductive-age women. Concentrations of several cytokines and angiogenic factors in peritoneal fluid (PF) have been found to correlate with the severity of the disease. However, levels of some analytes vary across the menstrual cycle, and an ideal biomarker of endometriosis has not yet been identified. We have compared the PF concentrations of different cytokines in proliferative and secretory phases in women with and without the disease using the Bio-Plex platform. Methods: PF was aspirated during laparoscopy (N = 133) and the PF concentrations of 18 cytokines from Bio-Plex panels I and II determined with the serum protocol. Results: Increased PF concentrations of IL-6, IL-18, eotaxin, and MCP-1 were found in endometriosis with no changes with menstrual cycle. Levels of IL-12(p70), ICAM-1, and GRO-alpha were higher in the secretory phase, while eotaxin concentrations were lower. Conclusion: Of the 18 cytokines tested, IL-6, IL-18 and MCP-1 were the best PF markers of endometriosis.