Autoantibody to the Liver Arginase Present in Sera of Patients with Autoimmune Hepatitis and Chronic Hepatitis

Abstract

We have reported previously that immunization of rat liver arginase in rabbits induced autoantibody that is reactive with their own liver arginase and has cytotoxic activity to their hepatocytes. This promoted us to investigate whether or not such an autoantibody is present in sera of patients with certain hepatic disorders, since the liver arginase is dominant in the liver and highly homologous in structure among ureotelic animals. By Western blot analysis, sera from patients with chronic hepatitis and autoimmune hepatitis were shown to have an autoantibody reacting with purified human liver arginase. Since the autoantibody was also reactive with liver arginase of rat origin to almost the same extent as that of human origin, ELISA with rat liver arginase as a coating antigen was developed and used for the quantification of the autoantibody. Prominent increase of the anti-liver arginase autoantibody was found in autoimmune hepatitis, moderate increase in chronic liver diseases, and no increase in acute hepatitis or normal controls by the ELISA. These results suggest that the increased anti-liver arginase autoantibody might involve in some parts in the pathophysiology of the hepatitic disorders. Assay of the autoantibody can also be utilized as a marker for the differentiation of certain hepatitis.