Serum IgA antibodies to human gut luminal aspirates and human liver in alcoholic liver disease

Background: Elevation of serum IgA is a characteristic feature of alcoholic liver disease. It has been proposed that this occurs partly as an antigenic response to gut-derived proteins or acetaldehyde-modified liver proteins, but the principal antigens responsible remain unknown. Aims The goal of this study was to determine if serum IgA antibodies were present against human gut luminal antigens or liver antigens in alcoholic liver disease. Patients and Methods: Twenty-nine patients with alcoholic liver disease, 10 with primary biliary cirrhosis, 12 with "other" liver diseases, 8 alcoholics, and 20 healthy subjects were studied. Western blotting was used to examine the reactivity of sera from these groups against human small and large bowel aspirates and liver tissue from alcoholic liver disease patients. Results: Serum IgA antibodies to a 140 kDa colonic luminal protein were found in 22 (76%) patients in the alcoholic liver disease group (p < 0.0001), and 7 (24%) patients had serum IgA antibodies to a 40 kDa colonic luminal protein (p = 0.04). These responses were confined to colonic aspirates and not observed in other disease groups, alcoholics or healthy subjects. There was no significant serum IgA response to human liver proteins in alcoholic liver disease. Conclusions Serum IgA antibodies to a human 140 kDa colonic luminal protein are frequently found in alcoholic liver disease. This novel antigen may contribute to the increased levels of circulating IgA in alcoholic liver disease.