[Hepatitis C immunology]

This review summarizes what is currently known about the cellular and humoral immune responses to hepatitis C virus. The results of viral protein immunogenicity studies reported so far are analyzed, and points of controversy about the immunology and immunopathology of hepatitis C are discussed. A body of evidence supports the existence in hepatitis C virus-infected subjects of strong humoral and cellular immune responses. HCV Core, NS3 and NS4 proteins are the most immunogenic antigens for B cells and HLA class II-restricted CD4+ T cells. For its part, liver-infiltrating CD8+ CTL recognize epitopes within the Core, E1, E2/NS1 and NS2 proteins in a HLA class I restricted manner. CTL responses to HCV Core, NS3, NS4 and NS5 have been detected in peripheral blood of patients chronically infected with HCV. Although these B and T cell responses may contribute to clear the virus, in most cases they are unable to resolve chronic HCV infections. No protective B or T cell epitope has been found yet. It is becoming clearer that the immune response plays a fundamental role in the pathogenesis of liver disease in hepatitis C patients.