Decreased amounts of antibodies to 22 and 18 kDa antigens in the peritoneal fluid of patients with endometriosis

Accumulated evidence implicates immunological alterations inendometriosis. The purpose of this study was to look for variationsin antibodies to distinct antigens in peritoneal fluid of womenwith and without endometriosis. Peritoneal fluid was aspiratedfrom 17 women undergoing laparoscopy for tubal ligation and37 patients complaining of symptoms of pain and/or infertility.Peritoneal fluid antibodies to a standard preparation of peritonealfluid antigens were detected by Western blot analysis usingperoxidase-labelled anti-human immunoglobulin G antibodies specificto the Fc region. Antibodies to distinct antigens were quantifiedby estimating the ratio of the relative optical density betweensamples and a standard amount of antibodies. Marked changeswere found in the antibody detection to two antigens havingapparent molecular weights of 22 and 18 kDa. The intensity ofthe antibody signal was significantly weaker in the peritonealfluid from endometriosis patients (0.36 ± 0.06 and 0.46± 0.06) compared with that in women without endometriosis(0.62 ± 0.08 and 0.75 ± 0.06). It was also weakerin patients without endometriosis presenting with infertility(036 ± 0.07 and 0.47 ± 0.08), but only the 18kDa antigen result was significant After adjusting for infertility,the P values for the 18 and 22 kDa bands were 0.03 and 0.28(not significant) respectively in the group of endometriosispatients. These changes were not related to the phase of themenstrual cycle. These data suggest an alteration in the immuneresponse to two distinct antigens in the peritoneal fluid fromwomen with endometriosis and infertility. Further evaluationof these two antigens and their antibodies would be of interestto help understand endometriosis and its associated infertility.