Apoptosis and the expression of Fas and Fas ligand (FasL) antigen in rejection and reinfection in liver allograft specimens

Background and Methods. To investigate the frequency of apoptosis and the expression of Fas/Fas ligand (FasL) in liver allografts, we examined 97 biopsy specimens from 62 patients after orthotopic liver transplantation. The results of the biopsies were as follows: acute allograft rejection (n = 32); hepatitis C virus (HCV) reinfection (n=18); cytomegalovirus infection (n=5); acute rejection plus HCV reinfection (n=3); and stable graft function (n=30); and after treatment of acute rejection (n=9), Results. Apoptotic cells were found in all cases examined, and their frequency increased significantly during acute rejection (0.17 vs. 9.0; P<0.05), The immunoreactivity of Fas and Fast antigen was higher in specimens with acute rejection than in those with stable graft function. Increased apoptosis, Fas, and Fast expression, however, were also seen in HCV reinfection, Conclusion. We conclude that apoptosis plays an important role in the hepatocellular damage observed in acute rejection and also in HCV reinfection. However, these parameters are, taken by themselves, not useful as indicators of acute rejection or HCV reinfection.