Vaccination with combination of Fit3L and RANTES in a DNA prime-protein boost regimen elicits strong cell-mediated immunity and antitumor effect.

With accumulating evidence indicating the importance of cytotoxic T lymphocytes (CTLs) in the antitumor response, strategies are being pursued to elicit augmented CD8(+) T-cell responses against tumors with tumor vaccines. Here, we report the protective efficacy of vaccine-elicited antitumor immune responses with an aggressive HBc-expressing B16-HBc melanoma, which expressed HBc as a self and model antigen, tumor model. We demonstrated that the significantly better memory responses or marked inhibition on tumor growth could be achieved after coadministration of cytokine adjuvants RANTES and Flt3L in a DNA prime-protein boost regimen. Furthermore, the augmentation of DNA prime-protein boost regimens by cytokines gene was due to the improvement the immunopotency of DNA vaccine and subsequently the augmented Ag-specific and IFN-gamma mediating CD8(+) T-cell responses after protein boosting. Hence, this study demonstrates for the first time that combinatorial use of chemotactic and potent DC-specific growth factor molecules provides a useful strategy for enhancing antitumor responses.