Detection of hepatitis C virus antibody in patients with autoimmune hepatitis and other chronic liver diseases.

To clarify the relationship between autoimmune hepatitis (AIH) and the hepatitis C virus (HCV), we investigated the prevalence of antibodies to HCV (anti-HCV) by an enzyme-linked immunosorbent assay in patients with AIH, primary biliary cirrhosis (PBC), rheumatoid arthritis and multiple myeloma. The antibody was detected in 9 out of 18 patients with AIH (50%), in 3 out of 23 with PBC (23%), in 2 out of 10 with rheumatoid arthritis (20%), and in 5 out of 9 with multiple myeloma (56%). However, the optical density values in these patients were lower than those observed in non-A, non-B hepatitis (NANBH). Anti-HCV became negative immediately after the initiation of glucocorticoid therapy in all four antibody-positive AIH patients tested. The extracted immunoglobulin G fraction from sera of 5 anti-HCV negative AIH patients became positive for the antibody. This phenomenon was not observed in 5 normal volunteer sera. The 9 family members of three anti-HCV positive AIH patients showed no anti-HCV positivity. These results suggest that autoantibodies in AIH patients may cross-react with the HCV-related antigen. Direct association of the HCV influencing the development of AIH is unlikely. Therefore, care should be taken in the evaluation of anti-HCV positivity in patients with autoimmune diseases and multiple myeloma.