Objective: To prepare a transgenic tumor cell vaccine transfected the fusion gene of murine granulocyte-monocyte colony stimulating factor (mGM-CSF) and human interleukin-2 (hIL-2) using H22 cells, and explore its specific antitumor immunity against hepatocellular carcinoma.
Methods: The eukaryotic vector expressing the fusion gene mGM-CSF/hIL-2 was transfected into H22 cells followed by radiation exposure to construct the tumor cell vaccine, which was used to immunize Balb/c mice by subcutaneous inoculation. The mice inoculated subcutaneously with H22 cells, cells transfected with the empty vector pcDNA(+), or with PBS served as the controls. A week later, H22 cells were injected peritoneally into Balb/c mice for establishing the tumor-bearing model, and their serum levels of interleukin-10 (IL-10) and interferon-gamma (IFN-gamma) were detected using enzyme-linked immunosorbent assay (ELISA) with the survival of the mice recorded. The spleen cells were obtained from the mice immunized with the tumor cell vaccine, the tumor-bearing mice and the normal control mice to assess their cytotoxicity against the parental H22 cells in vitro using (51)C(r)-release assay.
Results: The transgenic H22 cell vaccine transfected with mGM-CSF/hIL-2 fusion gene was successfully constructed. The killing rate of H22 cells by the spleen cells from the mice immunized with the transgenic cell vaccine was significantly higher than those by the spleen cells from the tumor-bearing mice or normal control mice (38.3% vs 13.6% and 7.5%, P<0.05). Serum IFN-gamma in the tumor-bearing mice immunized with the transgenic cell vaccine was significantly higher, and serum IL-10 significantly lower than those of the control groups (P<0.01). The survival time of the tumor-bearing mice injected with the transgenic cell vaccine was also significantly prolonged.
Conclusion: Syngeneic tumor cell vaccine genetically modified by mGM-CSF/hIL-2 fusion gene transfection can elicit specific cellular immune response and enhance the host antitumor immune response to extend the survival time of tumor-bearing mice.