Re-infection of the liver graft occurs universally following liver transplantation for HCV-induced end stage liver disease. Interestingly, the manifestation of HCV infection ranging from an asymptomatic carrier state to rapid progression to liver cirrhosis is extremely variable from one patient to another. The host and viral factors being responsible for the different course of HCV infection are poorly understood. Our study will focus on dendritic cells which are known to play a critical role in the control of viral infection. Viral factors (quasispecies evolution) will also be analysed and Th1 Th2 cytokines produced in the serum evaluated.Thirty liver transplanted patients will be included : 20 patients transplanted for HCV-related disease and 10 controls transplanted for non HCV-related disease. Blood samples will be taken just before transplantation and at different time -points up to 5 years after transplantation. Function of blood monocyte-derived DC will be evaluated. Circulating blood plasmacytoid (pDC) and myeloid DC (mDC) sub-populations will be enumerated. HCV quasispecies evolution will be analysed. This study may help to define prognostic markers on progression of hepatitis C in liver transplantation and allow the development of new immunotherapeutic drugs