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 p atients. Dendritic cells (DCs) are potent antigen-presenting cells that can prime naive T cells to induce a primary immune response. We attempted to i nduce preventive antitumor immunity against HCC by immunizing BALB/c mice w ith fusions of DCs and HCC cells. Methods. Murine bone marrow-derived DCs a nd a murine HCC cell line. BNL cells, were fused by treatment with 50% poly ethyleneglycol (PEG). Fusion efficacy was assessed by the analysis of fusio ns of BNL cells stained with red fluorescent dye and DCs stained with green fluorescent dye. Mice injected intravenously with DC/BNL fusions were chal lenged by BNL cell inoculation. Results. About 30% of the PEG-treated nonad herent cells with both fluorescences were considered to be fusion cells. Th e cell fraction of DC/BNL fusions showed phenotypes of DCs, MHC class II. C D80, CD86, and intercellular adhesion molecule (ICAM)-1. which were not exp ressed on BNL cells. Mice immunized with the fusions were protected against the inoculation of BNL tumor cells, whereas injection with a mixture of DC s and BNL cells not treated with PEG did not provide significant resistance against BNL cell inoculation. Splenocytes from DC/BNL fusion-immunized mic e showed lytic activity against BNL cells. Conclusions. These results demon strate that immunization with fusions of DCs and HCC cells is capable of in ducing preventive antitumor immunity against HCC.