Peritoneal fluid and serum autoantibody levels in patients with endometriosis

Patients with endometriosis demonstrate autoantibody abnormalities in their peripheral blood. Whether such abnormalities can also be detected in the peritoneal cavity, has not been established. We therefore investigated autoantibodies to 6 phospholipid antigens, 5 histones and histone subfractions and 4 polynucleotides in 14 laparoscopically diagnosed endometriosis and 9 control patients, undergoing laparoscopic tubal occlusion, in both serum and peritoneal fluid. Endometriosis patients demonstrated significantly lower total immunoglobulin G (IgG) levels in peritoneal fluid than controls. In contrast, specific IgG autoantibody levels were higher in peritoneal fluids of endometriosis patients. Mean antiphospholipids and antihistones autoantibodies reached significance when serum/peritoneal fluid ratios were compared with controls. Significant differences between endometriosis and control patients were restricted to IgG isotypes and were not observed for either IgM or IgA isotypes. These data suggest an abnormal concentration of IgG antiphospholipids and antihistones antibodies within the peritoneal cavity of endometriosis patients, which may play a contributing role in the peritoneal pathology of this condition.