Analysis of MAGE-3 derived synthetic peptide as a human lung cancer antigen recognized by cytotoxic T lymphocytes.

BACKGROUND

The human MAGE-3 gene was originally discovered in melanoma cells that encode tumor antigens, and has been reported to be expressed in various types of tumors, including lung cancer, but not in normal tissues other than testis or placenta. Our aim in this study was to clarify whether HLA-A2 restricted MAGE-3 peptide (FLWGPRALV) could be a lung cancer antigen recognized by cytotoxic T lymphocytes (CTL).

METHODS

MAGE-3-derived peptide-specific CTL were induced from the peripheral blood mononuclear cells (PBMC) of HLA-A0201-positive healthy donors and the regional lymph node lymphocytes (RLNL) of HLA-A2-positive patients with lung cancer by multiple stimulations with peptide-pulsed HLA-A0201-positive antigen-presenting cells.

RESULTS

Lymphocytes stimulated with MAGE-3 peptide exhibited specific lysis of Epstein-Barr virus-transformed B cells (EBV-B) pulsed with MAGE-3 peptide, but not with control peptide derived from influenza matrix protein, erbB-2, or wild type p53. Specific activity for MAGE-3-presenting targets was found after the second stimulation, and increased depending on the number of stimulations. The peptide-specific activity was inhibited by the addition of monoclonal antibodies against MHC class I and HLA-A2. Such CTL also recognized tumor cell lines expressing both HLA-A2 and MAGE-3 in an MHC class I-restricted manner, but did not recognize tumor cell lines that did not express HLA-A2 or MAGE-3.

CONCLUSION

These results suggested the MAGE-3 peptide could be a potential target of specific immunotherapy for HLA-A2 patients with lung cancer.