ANTIBODIES TO CARBONIC-ANHYDRASE IN PATIENTS WITH IMMUNE CHOLANGIOPATHIES

Background/Aims: Bile duct epithelia contain an abundance of carbonic anhydrase. Antibodies to this enzyme have been described in autoimmune disorders. Serum from patients with immune-mediated liver diseases wa s studied to determine whether antibodies to carbonic anhydrase II and /or pyruvate dehydrogenase could distinguish autoimmune cholangitis as immunologically distinct from primary biliary cirrhosis. Methods: Ant ibody assays to carbonic anhydrase II (Western blot) and pyruvate dehy drogenase (flow cytometry) were performed on the sera of patients with autoimmune cholangitis (6), primary biliary cirrhosis (12), primary s clerosing cholangitis (12), autoimmune hepatitis (12), and control (Gi lbert syndrome; 8). Results: Reactivity to carbonic anhydrase II was d etected in 5 of 6 patients with autoimmune cholangitis, 1 of 12 patien ts with primary biliary cirrhosis, 1 of 12 patients with autoimmune he patitis, and no other patients. Individuals with autoimmune cholangiti s were more likely than the other patients to be reactive to carbonic anhydrase Il (P < 0.001). Patients with primary biliary cirrhosis were more reactive to pyruvate dehydrogenase compared with all other group s (P < 0.001). Conclusions: An antibody to human carbonic anhydrase II is frequently detected in the sera of patients with autoimmune cholan gitis and is uncommon or not present in other cholangiopathies. These data provide evidence that autoimmune cholangitis and primary biliary cirrhosis represent distinct entities with unique patterns of immunore activity.