Immunization With Dendritic Cells Transfected With Human KDR MRNA Elicits Immunity Against Mouse Hepatocellular Carcinomas

[Objective]:To investigate the effects of dendritic cells(DCs) transfected with mRNA encoding kinase domain-containing receptor(KDR) on breaking the immune tolerance and induction of immunity against hepatocellular carcinomas.[Methods]:Construction of pmRNA IRES-hKDR and pmRNA IRES-mKDR were purformed by molecular coloning technology. IRES- hKDR mRNA was generated successfully in vitro using MEGAscript SP6 kits.Bone marrow precursor-derived dendritic cells (BMDCs) are generated from bone marrow progenitors as Lutz's described with some modification.Mice were immunized with hKDR or mKDR mRNA transfected DCs and in vitro CTL activity against Hepa1-6 cells was examined by standard LDH release assay.Survival of the immunized mice was evaluated with hKDR mRNA/DCs or mKDR mRNA/DCs.[Results]:The activity of CTL elicited by the hKDR- transfected DCs was much stronger than that by mKDR- transfected DCs. In 100:1,50:1,25:1 proportion, the killing rates of CTL activated by hKDR mRNA/DCs were 71.6%,55.8%,22.7%,mKDR mRNA/DCs were 48.2%,30.2%,15.4%,DCs without being modified were 19.2%,12.3%,6.9%. There are significant difference between each same proportion two groups(p<0.05).80% of the hKDR mRNA/DCs-immunized mice of the inoculated with 1×106 Hepa1-6 hepatoma cells were still alive two months after inoculation.However,the mKDR mRNA/DCs-immunized mice inoculated with 1×106 Hepa1-6 hepatoma cells were just 20% surviving two months later.[conclusion]: mRNA vector-mediated xenogeneic KDR-infected DCs can effectively break the immune tolerance to hepatocellular carcinomas in an animal model and induce strong antigen-specific T cell response.