Detection of antiendometrial antibodies in sera of patients with endometriosis by dual-colored, double-labeling immunohistochemical method and western blot

PROBLEM: This study was undertaken to determine whether specific binding activities against endometrial proteins in sera of patients with endometriosis are detectable and, if so, to identify endometrial antigens involved in autoimmunity in endometriosis. METHOD: Sera from 33 patients with endometriosis and 20 cord sera (controls) were tested against endometria of patients and their protein extracts by dual-colored, double-labeling immunohistochemical method, and Western blotting. RESULTS: Antiendometrial binding activities were detected in sera of 2 (10.0%) control patients and 13 (48.2%) patients with endometriosis by the immunohistochemical method. Endogenous immunoglobulin G (IgG) binding to endometrial proteins had molecular weights (MW) of 26, 28, 54, 85, 107 and 116 kDa. Most sera of both control and patients showed reactivity against endometrial proteins with MW of 34, 36, 56 and 77 kDa. However, there were specific IgG autoantibodies reactive against the endometrial proteins of 71, 92, and 103 kDa in sera of 55.2% (16/29) of patients but not in the control sera. Over 80% (10/12) of patients' sera with binding activities detectable by the immunohistochemical method also tested positive by Western blot analysis. CONCLUSIONS: These data show that specific IgG antibodies reactive against endometrial antigens are detectable in sera from some patients with endometriosis.