Engineered fusion hybrid vaccine of IL-18 gene-modified tumor cells and dendritic cells induces enhanced antitumor immunity.

Dendritic cell (DC)-tumor fusion hybrid vaccines that facilitate antigen presentation represent a novel powerful strategy in cancer immunotherapy. In our study, we investigated the antitumor immunity derived from the vaccination of fusion hybrids between engineered J558/IL-18 myeloma cells secreting Th1 cytokine IL-18 and DCs. DC/J558/IL-18 could secret a higher level of IL-18 than DCs, efficiently expressed J558 tumor antigen P1A, and enhanced ability of allogeneic T cell stimulation when compared to J558/IL-18. Our data showed that the immunization of BALB/c mice with DC/J558/IL-18 hybrids induced the most potent protective immunity against 1 x 10(6) cells with a J558 tumor challenge, compared to those immunized with the mixture of DCs and J558/IL-18, J558/IL-18, or J558. Furthermore, the immunization of mice with engineered DC/J558/IL-18 hybrids elicited stronger NK activity and J558 tumor-specific cytotoxic T lymphocyte (CTL) responses in vitro. In addition, DC/J558/IL-18 tumor cells into syngeneic mice induced a Th1 dominant immune response to J558 and resulted in tumor regression, which indicated that the antitumor effect mediated by DC/J558/IL-18 appeared to be dependent on TH1 cytokine production. These results demonstrate that the engineered fusion hybrid vaccines that combine Th1 gene-modified tumor with DCs may be an attractive strategy for cancer immunotherapy.