Different concentrations of interleukins in the peritoneal fluid of women with endometriosis: relationships with lymphocyte subsets

The present study explored the possible relationships between immune cell subsets and interleukin (IL)-12 or IL-13 levels in the peritoneal fluid of patients with and without endometriosis. Peritoneal fluid samples were obtained from 80 women while they were undergoing laparoscopy for pain, infertility, tubal ligation or re-anastomosis. The American Fertility Society scoring system was used to determine the extension of endometriosis. The peritoneal fluid mononuclear cells were analyzed for immunophenotyping using cytometry, whereas peritoneal fluid concentrations of interleukins were measured using two ultrasensitive commercially available enzyme-linked immunosorbent assay kits. Significantly higher peritoneal fluid IL-12 levels were found in women with moderate or severe endometriosis (stages III and IV) than in healthy controls (p < 0.01). Conversely, subjects with endometriosis showed remarkably lower peritoneal fluid IL-13 concentrations than controls, independent of the severity of the disease (p < 0.05). Considering immune system effectors, patients with endometriosis presented a significantly higher peritoneal fluid CD8(+)/CD4(+) ratio when compared with healthy controls. Moreover, the number of peritoneal fluid CD8(+) and CD4(+) activated T cells was significantly lower in the former than in the latter group, independent of the endometriosis stage. Connections were observed between peritoneal fluid interleukins and peritoneal fluid T cells: both patients with endometriosis and controls presented an inverse correlation between peritoneal fluid activated T cells and IL-13 levels, and a direct correlation between peritoneal fluid T cells and IL-12 concentrations. These data seem to suggest that a reciprocal modulation exists between peritoneal fluid cytokines and T lymphocyte subsets in patients with endometriosis.