Peritoneal interleukin-10 increases with decrease in activated CD4⁺ T lymphocytes in women with endometriosis

This study was performed to determine whether peritoneal T cells are suppressed in the CD4⁺ or CD8⁺ T cell subpopulation and whether they are Th1 or Th2 predominant in women with endometriosis. Immune cells in the peritoneal fluid (PF) were obtained from women undergoing laparoscopy for endometriosis or tubal ligation. Three-colour flow cytometry was utilized for immunophenotyping of peritoneal fluid mononuclear cells (PFMC). Concentrations of interleukin (IL)-4, IL-5 and interferon-γ (IFN-γ) produced by PFMC with and without mitogen stimulation and concentrations of IL-10 and IL-12 were measured in PF. The peritoneal T lymphocytes were predominantly of the Th1 type that produced much more IFN-γ but less IL-4 or IL-5 in women with or without endometriosis. The decrease in peritoneal lymphocytes was significant in the HLA-DR⁺CD4⁺CD3⁺ subpopulation and the concentrations of peritoneal IL-10 and IL-12 were significantly elevated in women with early stage endometriosis. There was impaired IL-5 production by PFMC after phytohaemagglutinin stimulation in women with advanced stage endometriosis. We concluded that the activated peritoneal CD4⁺ Th1 cells from the women with endometriosis were decreased in number. The suppression of these T cells may be due to the elevation of IL-10 and IL-12 in the peritoneal fluid.