Characterization of a MAGE-1-derived HLA-A24 Epitope-specific CTL Line from a Japanese Metastatic Melanoma Patient

A MAGE-1 HLA-A24 peptide-specific CTL line was characterized using a novel staining approach in the case of a metastatic melanoma patient who exhibited a remarkable clinical response in HLA-A24 peptide cocktail-pulsed dendritic cell (DCs) vaccine therapy. Briefly, pre- or post-vaccine peripheral blood mononuclear cells (PBMCs) from the vaccinated patient were stimulated several times with MAGE-1 A24 peptide-pulsed DCs and T2-A24 cells in vitro. Expanded MAGE-1 A24-specific CTL line was investigated in terms of immunological functions. The proportion of MAGE-1 A24 tetramer + CTLs increased from 0.04% to 18.6%, and the absolute numbers of MAGE-1 tetramer + CTLs increased up to 5,068-fold after stimulations. Expanded CTL line exhibited a strong cytotoxic activity against MAGE-1 + cancer cell line in the restriction of HLA. Finally, successful identification of MAGE-1 A24 peptide-specific T-cell receptor (TCR) cDNA from anti-TCR MoAb-sorted CTL was obtained for the first time and the specific cytotoxicity in TCR gene-transduced naive T-cells was confirmed.