Specific IFN-γ by ELISPOT assay. The PBMCs of human HLA-A2+ donors were obtained and then cultured in RPMI 1640 supplemented with 10 % FCS, 100 U/ml penicillin, and 100 μg/ml streptomycin. Dendritic cell were generated, and loaded with different peptides at a final concentration of 100 μg/ml for 4 h and were then irradiated with 20 Gy, which prevented all outgrowths in the control cultures. Autologous T cells were restimulated every 7 days with the peptide-pulsed DCs to generate peptide-specific CTLs. The IFN-γ secretion was then assessed on day 23. Experiments performed in triplicate showed consistent results. Compared with controls, P < 0.05