Immunoglobulin M and A antibodies to hepatitis C core antigen in chronic hepatitis C virus infection.

To determine the prevalence and clinical significance of IgM and IgA antibody to hepatitis C virus (HCV) core antigen in chronic HCV infection, sera from 47 patients were tested for immunoglobulin class M (IgM) and immunoglobulin A (IgA) antibody to HCV core antigen by solid-phase enzyme-linked immunoassay using a recombinant core protein (aa1-150). Results were correlated with the clinical, biochemical and histological parameters, serum HCV RNA levels (determined by branched DNA signal amplification assay), and subsequent clinical response to interferon-alpha therapy. IgM anti-HCV core was detected in 11 patients (23.4 percent). There was no correlation between the presence of IgM anti-HCV core and the clinical features (sex, age, mode of acquisition), biochemical parameters (serum ALT, AST, alkaline phosphatase, and albumin level), autoimmune markers [serum globulin levels, anti-nuclear antibody (+ at < 1:80 in 7/47 patients)], serum HCV RNA levels, subsequent response to interferon-alpha therapy, and the histological features. Immunoglobulin A anti-HCV core was not detected in any of the patients. The presence of IgM ant-HCV core in a proportion of patients with chronic HCV infection indicates that the presence of serum IgM anti-HCV core may not be unique to acute HCV infection.