PROTECTION AND DEFENSE-MECHANISMS IN HCV INFECTION

The immune response triggered by hepatitis C virus (HCV) infection is still poorly documented and its underlying mechanisms are still to be elucidated. Following infection, both humoral and cellular responses a re directed at multiple determinants (polyclonal) involving most of th e viral antigens. These responses apparently involve neutralizing anti bodies as well as peripheral and liver infiltrating cytotoxic T lympho cytes (CD8+) and proliferative reaction associated with CD4+. In most cases these responses cannot control infection. In addition, re-infect ion following an episode of self-limited infection or during chronic c arrier condition has been described in chimpanzees and in man. Among t he factors that may influence immune response by the host are the poss ible existence of extra-hepatic sites capable of supporting viral repl ication (in particular of haematopoietic origin) as well as the existe nce of complexed viral particles (such as with immunoglobulins and lip id components).