[Immunotherapy with a chimeric AFP and HSP70 gene DNA vaccine targeting on a murine hepatocellular carcinoma].

ABSTRACT

OBJECTIVES: To investigate immune responses and the anti-tumor effect of a constructed Chimeric AFP-Mt.HSP70 DNA vaccine in mice. METHODS: Chimeric AFP-Mt.HSP70 was constructed by molecular clone techniques. Spleen cells derived from mice immunized twice were induced to secrete IFN gamma and were assayed using ELISA. The activity of the cytotoxic lymphocytes (CTL) derived from spleen cells was assayed using lactate dehydrogenase (LDH). 4 x 10(6) Hepa1-6 cells/200 microl were injected subcutaneously into the right axilla of each mouse bearing the tumor. The anti-tumor effect of the recombinant DNA vaccine was evaluated by measuring tumor sizes of the mice. RESULTS: AFP-specific CTL reaction was induced by our chimeric DNA vaccine and Mt.HSP70 enhanced this effect (P < 0.05). The CTL activity was about 32% at E/T=501. The IFN gamma secreted by spleen cells of mice immunized with chimeric plasmids was about 200 pg/ml. It was higher than those in the other groups; Tumor sizes of mice immunized with fused plasmids were smaller than those in the other groups. Survival times of mice immunized with the fused plasmids were prolonged. CONCLUSION: Chimeric DNA vaccine can induce AFP-specific CTL reaction and has an anti-tumor effect on transplanted tumors in our murine experiment.