The potential of the nine peptides in stimulating the human CD8+ T cells was also determined. Two groups of CD8+ T cells isolated from PBMC of two healthy donors, respectively, were primed with autologous mature NP-loaded DC three times. Intracellular cytokine staining was performed to detect the release of IFN-c from the CD8+ T cells, and the peptide-loaded T2 cells were used as the target cells. NP once processed by DC, will combine with the HLA molecules and eventually become presented on the cell surface for the priming of the CD8+ T cells. The primed CD8+ T cells could therefore recognize the peptide-MHC complex on the T2 cells if the target peptides are processed and presented on the DC surface. The results from intracellular cytokine staining showed that the highest number of CD8+ IFN-c-secreting T cells was produced after the stimulation with the NP189 (MVME-LIRMI), NP373 (AMDSNTLEL), and NP458 (FQGRGVFEL) peptides, and the lowest number of the stimulated T cells was observed after stimulation with the NP158 (GMDPRMCSL) peptide. The N160 (LQLPQGTTL) peptideloaded T2 cells used as a negative control did not show any significant changes (Fig. 2) [2] .