Flow cytometry analysis of lymphocyte subpopulations in peritoneal fluid of women with endometriosis

PROBLEM: We investigated the lymphocyte subpopulations in peripheral blood (PB) and peritoneal fluid (PF) of women with and without endometriosis to evaluate if the decreased natural killer (NK)-mediated cytotoxicity in women with endometriosis was due to a quantitative defect or not. METHOD: The PB and PF mononuclear cells of 59 women undergoing a diagnostic laparoscopy for pain and/or infertility were analyzed by flow cytometry. RESULTS: The number and concentration of PF mononuclear cells (MC) was increased in women with endometriosis compared to women without endometriosis. The monocyte/macrophage marker (CD14) was expressed on 70.3 and 66.9% of PFMC of women with and without endometriosis, respectively. The CD4/CD8 ratio was inverted in the PF, and this was more pronounced in women with endometriosis. In the PF of women with endometriosis, 41.3% of the lymphocytes were CD8 positive, compared to 34.3% in women without endometriosis. The percentage of NK positive lymphocytes in PF, using three different monoclonal antibodies directed against NK cell markers (CD57, CD16, and CD56) were not different between women with and without endometriosis. In women with endometriosis, 12.7, 9.5, and 28.8% of lymphocytes were CD57, CD16, and CD56 positive, respectively. CONCLUSION: PFMC consisted mainly of phagocytic and human leukocyte antigen (HLA)-restricted or HLA unrestricted cytotoxic cells capable of reacting to various antigens entering the cavity from the lower genital tractus. Furthermore, the decreased NK activity reported in PB and PF of women with endometriosis was not likely to be caused by a quantitative defect, since the percentage of NK positive lymphocytes was not different between women with and without endometriosis.