ABSTRACT
AIM:Peptide vaccines have been conceived as promising therapies for tumor-inflicted patients due to their easy production and capability of inducing specific immune response required for defending the tumor.During our previous research,4 HLA-A2-restricted peptides had been identified as immunogenic in vivo.In this study, we aimed to testify the in vivo immunogenicity of the 4 peptides.METHODS: BALB/c mice were vaccinated with HLA-A2 restricted peptides emulsified in incomplete Freund's adjuvant(IFA)subcutaneously in combination with the epitope at the adjacent location.After the 3rd peptide vaccination for 10 d,the peptide-specific immune response was evaluated by ELISPOT and ELISA.The ability to induce T cell response was investigated by using cytotoxicity assay in vivo and the presence of pep-tide-specific CD8+T cells capable of recognizing the MHC-peptide was detected by flow cytometry.RESULTS: Among the 4 candidate HLA-A2 restricted peptides,the immune response elicited by P2004-1Y9V was superior to that of the other 3 peptides.The CTLs induced by P2004 and P2004-1Y9V lysed CAPAN-2 cells.P2004-1Y9V peptide-specific CTLs showed higher cytotoxicity against pancreatic tumor cell lines of CAPAN-2 than the native peptide-specific CTLs.Intracellu-lar cytokine staining assay indicated the presence of P 2004-1Y9V specific CD8 +T cells in the P2004-1Y9V vaccinated mice.CONCLUSION:P2004-1Y9V is the most immunogenic peptide in vivo, and can be explored as potential tumor peptide vaccine in the future clinical study.