INTERNALMEDICINE : Vol. 45 (2006) , No. 4 pp.183-191

Immunopathogenesis of Hepatitis C Virus Infection: Multifaceted Strategies Subverting Innate and Adaptive Immunity

Tatsuya Kanto¹⁾²⁾ and Norio Hayashi¹⁾

1) Department of Gastroenterology and Hepatology, Osaka University Graduate School of Medicine
2) Department of Dendritic Cell Biology and Clinical Applications, Osaka University Graduate School of Medicine

Abstract
Hepatitis C virus (HCV) infection is one of the major causes of chronic liver disease worldwide. The critical role of innate as well as adaptive immunity has been reported in HCV persistence and liver injury. In the early phase of acute infection, HCV continues to replicate in the liver, suggesting the HCV capability of inhibiting innate immunity. The sustained, vigorous and multiepitopespecific CD4⁺ and CD8⁺ T cell responses are essential for spontaneous HCV clearance. HCVspecific CD8⁺ T cells are primary elements for HCV clearance by inducing hepatocyte apoptosis, in which Fas/CD95 is fundamentally involved. However, once HCV persistency develops, HCV utilizes multifaceted arms to subvert various immune effectors. During IFNαbased therapy, the enhancement of HCVspecific CD4⁺ T cell response followed by HCV eradication has been reported, however, it remains obscure whether the therapeutic HCV clearance is able to restore the durable immune competency to HCV. Further investigation is still warranted to establish the means to direct HCVspecific immune responses in the desired way.

Key words:

innate immunity, adaptive immunity, dendritic cells, apoptosis