HCV infection is characterized by chronic immune activation and increasing array of immune dysfunetions[Gerlach et al, 1999; Nascimbeni et al, 2003].An early and persistent Thl一dominated CD4 response, whichis critical in the prevention of the chronically infected state [Lechner et al, 2000]，is particularly impaired, anddefects appear during a chronic course in disease [Rosen, et al, 2002; Ulsenheimer, et al, 2003].The basis ofHCV一specific CD4+T cell immune dysfunction has not been fully elucidated. In this regard, one avenue thathas not been explained fully in relation to HCV一specific immune responses is the potential role of host一mediatedimmunosuppressive mechanisms that might be activated in the face of persistent antigenic exposure.