DNA immunization of the grafted liver by particle-mediated gene gun

Background. Direct DNA vaccination of liver allografts before transplantation may provide an effective strategy for inducing protective immunity to infection and malignancy. Methods. In this study, the authors examined the feasibility of gene gun-mediated vaccination of liver grafts. Using plasmids expressing luciferase and green fluorescent proteins, their expression was tested in a graft liver. Results. Protein expression was observed in the graft liver and significantly enhanced in hepatectomized rats. A short course of tacrolimus (FK506) also evoked the expression of these proteins. Effects of primary immunization to the liver on the humoral response were then tested using an expression plasmid encoding hepatitis B virus surface (HBs) antigen and were compared to that of skin immunization alone. The results showed that local immunization to the liver strongly induced antibody formation. Furthermore, the combination of an immunized partial liver graft with tacrolimus significantly enhanced antibody production against HBs antigen. Conclusions. A DNA vaccine to the liver may be one strategy for preventing infectious disease associated with liver transplantation under tacrolimus treatment.