Ad-hDCT (tumor vaccine) inhibiting the proliferation of intracranial B16 melanoma cells in C57BL/6 mice

Objective: To observe inhibitive effect on the intracranial B16 melanoma cells in C57BL/6 mice by vaccination with Ad-hDCT. Methods: Forty C57BL/6 mice were divided to 2 groups: Ad-BHG control group and Ad-hDCT treatment group. B16-F10 cells were planted into the brain by mouse stereotaxic apparatus. General observation, flow cytometry, paraffin sections with HE staining, frozen sections with CD8 and F4/80 immunohistochemistry detection were adopted in this study. Results: Seven days after vaccination with Ad-hDCT, the level of hDCT specific CD8 ⁺ INF-γ ⁺ T cells increased significantly in the peripheral blood of the mice (P < 0.01 vs Ad-BHG group). Compared to 100% endpoint of Ad-BHG blank vector control, the survival rate was 60% in Ad-hDCT immunized group after B16 cells plantation in parenchyma 16 days. The mice behaviour was normal. Histological analysis indicated that no tumor cells proliferated in the vaccinated mice. CD8 ⁺ T cells were detected in the tumor mass to recognize and kill tumor cells in vaccinated animals. Furthermore, much more microglia were found around the tumor area in the brain of the vaccinated mice. Conclusion: Ad-hDCT can elicit a strong cytotoxic T lymphocyte (CTL) response in C57BL/6 mice, leading to protection against intracranial challenge with B16 melanoma cells.