Changes in antibody titers to hepatitis C virus following interferon therapy for chronic infection.

The use of quantitative assays for hepatitis C virus specific antibodies (anti-HCV) as a prognostic marker was evaluated in 31 patients with chronic hepatitis C treated with interferon (IFN). Changes in titers of serum HCV-RNA and anti-HCV antibodies; anti-C11 (anti-core), anti-C100 (anti-NS3), and anti-C7 (anti-NS3) were investigated. Recombinant IFN-alpha 2a was administered and the patients were followed for more than 1 year. The patients were classified into three groups according to their responses to IFN: 11 sustained responders with continuous normalizations of serum alanine aminotransferase (ALT) levels; 14 transient responders with transient decreases in ALT; and six nonresponders who had no changes in ALT levels. Ten of 11 sustained responders had a continuous decrease in anti-C11 titers after completion of treatment, decreasing to less than half of pretreatment titers. No patients in the other two groups had a continuous decrease in anti-C11 titers. Although sustained responders had decreases in anti-C100 and anti-C7 titers after IFN therapy, these titers also decreased in some patients in the other two groups. HCV-RNA was not detected in the sera of 10 of 11 sustained responders following IFN therapy. In contrast, while 9 of 10 transient and non-responders had a decrease or disappearance of HCV-RNA at the completion of therapy, they had increased levels thereafter. These results indicate that anti-HCV-core (anti-C11) titers most closely reflect the status of HCV replication. A quantitative assay for anti-HCV-core antibody can be used as a predictive marker of remission in IFN-treated patients with chronic hepatitis C.