Pathogenesis of chronic hepatitis C virus infection.

HCV-infected patients with chronic liver disease have evidence of circulating HCV-specific antibodies and a polyclonal, multi-specific T cell response. CD4+ proliferative responses and HCV-specific CTLs directed against one or more viral antigens are readily detected in those individuals who develop chronic HCV infection and appear to compartmentalize within the liver. Cytokines, which are produced locally within the liver and systemically, may play an important role in controlling viral replication and contributing to hepatocellular damage. However, neither the humoral nor cellular immune response, nor the cytokine response appears sufficient to eradicate infection in most patients. In its attempt to clear the virus from the liver, the immune system contributes to the hepatocellular injury seen in the majority of chronically infected patients. A better understanding of the host's immune response may provide further insight on the pathogenetic mechanisms involved in development of chronic hepatitis and aid the development of better therapeutic strategies.