Preventive antitumor activity against hepatocellular carcinoma (HCC) induced by immunization with fusions of dendritic cells and HCC cells in mice

Background. The prevention of recurrence of hepatocellular carcinoma (HCC) after treatment is very important for improvement of the prognosis of HCC patients. Dendritic cells (DCs) are potent antigen-presenting cells that can prime naive T cells to induce a primary immune response. We attempted to induce preventive antitumor immunity against HCC by immunizing BALB/c mice with fusions of DCs and HCC cells. Methods. Murine bone marrow-derived DCs and a murine HCC cell line. BNL cells, were fused by treatment with 50% polyethyleneglycol (PEG). Fusion efficacy was assessed by the analysis of fusions of BNL cells stained with red fluorescent dye and DCs stained with green fluorescent dye. Mice injected intravenously with DC/BNL fusions were challenged by BNL cell inoculation. Results. About 30% of the PEG-treated nonadherent cells with both fluorescences were considered to be fusion cells. The cell fraction of DC/BNL fusions showed phenotypes of DCs, MHC class II. CD80, CD86, and intercellular adhesion molecule (ICAM)-1. which were not expressed on BNL cells. Mice immunized with the fusions were protected against the inoculation of BNL tumor cells, whereas injection with a mixture of DCs and BNL cells not treated with PEG did not provide significant resistance against BNL cell inoculation. Splenocytes from DC/BNL fusion-immunized mice showed lytic activity against BNL cells. Conclusions. These results demonstrate that immunization with fusions of DCs and HCC cells is capable of inducing preventive antitumor immunity against HCC.