Antibodies to hepatitis C virus envelope proteins correlate with hepatitis C viraemia after liver transplantation

Background. Liver transplant recipients for hepatitis C virus (HCV)-related cirrhosis usually remain anti-HCV-seropositive after transplantation. The aim of this study was to characterize, longitudinally, the profile of HCV-specific antibodies and cryoglobulins in liver transplant recipients with recurrent HCV infection. Methods. Serial serum samples were collected prospectively before, at 1 month after, and at 12 months after transplantation for HCV cirrhosis in 30 patients infected with genotype 1. The antibodies against HCV envelope proteins (E1 and E2) were quantitated by enzyme-linked immunosorbent assay and antibodies against core, E2/hypervariable region I (HVRI), NS3, NS4, and NS5A antigens by a line immunoassay. Sera were also tested for cryoglobulins. Results. The titer of each anti-HCV antibody had fallen at 1 month after transplantation (P<0.05) with the exception of anti-E1 levels, which had risen in 16 patients with acute hepatitis C at that time (P=0.01). Anti-E1 and anti-E2 titers, but not antibodies against other HCV antigens, increased to pre-transplantation levels or higher at 12 months, which correlated with serum HCV RNA levels. Cryoglobulinemia was present in nine patients after transplantation (30%) and was associated with lower anti-E1 levels (P=0.04) and more severe graft damage. Conclusions. The early increase in antibodies to HCV envelope proteins in correlation with viremia suggests that the envelope-specific humoral immune response may be directly stimulated by HCV replication. Anti-E1 levels may be a useful marker in monitoring patients with recurrent HCV infection.