Representative immunological monitoring assays detecting antigen-specific CTL response in a patient belonging to the 24(+) group. PBLs obtained from case 2 patient (HLA-A*2402 positive) after the 10th vaccination were cultured in rIL-2 for 14 days with 2 times of LY6K-peptide stimulation. (A) The cultured lymphocytes were subjected to the ELISPOT assay after depletion of CD4-positive cells by magnetic beads. TISI cells were incubated with responder cells in the presence of LY6K peptide or HIV peptide as an irrelevant control, and the spot counts were quantified (B). (C) The cultured lymphocytes were analyzed with HLA-A2402/LY6K-pentamer in the combination with CD8 and CD3 mAbs with flow cytometry. The value of pentamer (+)/CD8(+) among CD3(+) cells was shown. R/S, responder/stimulator.