T-CELL IMMUNITY IN HEPATITIS-C VIRUS-INFECTION

The hepatitis C virus (HCV) is the etiologic agent of most cases of no n-A, non-B hepatitis and is associated with persistent infection and c hronic liver disease in up to 90% of cases. However, chronic hepatitis C patients seem to be immunologically normal, and it is well known th at HCV is able to elicit both humoral and cellular immune responses. A lthough the mechanisms by which HCV escapes immune 'clearance' thus in ducing chronic hepatitis are not yet well understood, several studies seem to indicate that hepatocellular damage in chronic HCV infection m ay result from activation of cytotoxic T lymphocyte (CTL) responses, r ather than from a direct cytopathic effect. CTL responses represent a major defense mechanism in viral infections, but in chronic hepatitis C patients the virus is able to survive in spite of strong CTL respons es. Several mechanisms may account for the ineffectiveness of the immu ne response in these patients. This short review focuses on the possib le strategies exploited by HCV in order to avoid immune clearance, wit h particular emphasis on the mechanisms affecting the cellular arm of the immune system. (C) 1998 Elsevier Science Ireland Ltd. All rights r eserved.