Pathobiology of hepatitis C.

Hepatitis C virus (HCV) represents the major etiologic agent of non-A, non-B hepatitis. The pathological changes in hepatitis C are characterized by the histologic triad of lymphoid aggregates in portal tracts, epithelial damage of small bile ducts, and micro- and macro-vesicular steatosis. HCV antigens are demonstrable in the cytoplasm of infected hepatocytes by immunohistochemical staining with mono- or polyclonal antibodies, particularly when frozen tissues are employed. Detection of HCV RNA sequences in fixed liver tissues by in situ hybridization appears to be a more sensitive method than immunohistochemical staining. These studies are important to determine the viral load and expression pattern of HCV in the infected liver. The mechanism of hepatocyte and bile duct injury in HCV infection appears to be related to the host immune response to the virus, although direct viral cytopathogenicity may also pay a role.