Abstract: Objective To investigate whether ornithine decarboxylase antizyme inhibitor-1(OAZI-1) can enhance the immunogenicity of Melan-A and induce antitumor immune effect in the experimental animals or not. Methods The eukaryotic expression plasmid pcDNA3.1(-) /OAZI-1, pcDNA3.1 (-)/Melan-A and pcDNA3.1(-)/ Melan-A-OAZI-1 were constructed and used to immune BALB/c mice. The spleen lymphocytes were prepared from the immunized mice and then used to determine the lymphocyte subsets by flow cytometry assay and tumor-killing activity by LDH release assay. The blood samples were collected from the immunized mice and used to test the serum INF-γ levels by ELISA. Results The eukaryotic expression plasmid pcDNA3.1(-)/OAZI-1, pcDNA3.1(-)/Melan-A and pcDNA3.1(-)/ Melan-A-OAZI-1 were constructed successfully. All three gene vaccines could increase CD4+ T cell ratio (p<0.05), among of them, the ratio in the pcDNA3.1(-)/Melan-A-OAZI-1 and pcDNA3.1(-)/Melan-A immune groups increased more significantly than other groups but no obvious differences was observed between these two groups. Similarly, all three gene vaccines could also increase CD8+T cells ratio significantly (p<0.05), but, comparing with all other groups, the highest increase was observed in the pcDNA3.1(-)/Melan-A-OAZI-1 immune group (p<0.05). The pcDNA3.1(-)/ Melan-A-OAZI-1 gene vaccines could significantly increase cytotoxic activity of the spleen lymphocyte in the immune mice(p<0.05). Among the three gene vaccines only pcDNA3.1(-)/Melan-A-OAZI-1 could significantly increase the INF–γ level in the mice serum (p<0.05). Conclusion OAZI-1 can increase antitumor immunity by promoting tumor antigen presentation.

Key words: ornithine decarboxylase antizyme inhibitor-1, Melan-A, tumor, immunogenicity