INDUCTION OF ANTITUMOR CYTOTOXIC T-LYMPHOCYTES FROM THE PERIPHERAL-BLOOD MONONUCLEAR-CELLS OF CANCER-PATIENTS USING HLA-A2-RESTRICTED MAGE-3 PEPTIDE IN-VITRO

As the basis for the application of MAGE antigens to therapeutic use, the induction of peptide-specific CTLs has been investigated by the st imulation of peripheral blood mononuclear cells (PBMCs) with antigenic peptides derived from MAGE genes, However, the cross-reactivity of th e peptide-induced CTLs to the target cells endogenously presenting the MAGE epitope, especially in cancer patients, remains controversial, d espite the use of complicated manipulations, Because we recently devel oped a new simplified method to induce peptide-specific CTLs that kill ed MAGE expressing tumor cells from the PBMCs of a healthy donor, we e xamined the induction of specific CTLs by stimulation of PBMCs with HL A-A2-restricted MAGE-3 peptide in HLA-A2(+) cancer patients whose tumo rs expressed MAGE-3 by using the simple method, The CTL responses coul d thus be induced from unseparated PBMCs by stimulation with freshly i solated, peptide-pulsed PBMCs as antigen-presenting cells and by using interleukin 7 and keyhole limpet hemocyanin for the primary culture, All CTLs induced from the PBMCs of four cancer patients tested could t hus lyse the HLA-A2 target cells pulsed with the peptide, and moreover , two of the CTLs were also able to kill HLA-A2 tumor cells expressing MAGE-3 in a HLA class I and A2-restricted manner, Therefore, these fi ndings seem to indicate that HLA-A2-restricted MAGE-3 peptide may be p otentially useful for specific immunotherapy in cancer patients.