A MAGE-A1 peptide presented to cytolytic T lymphocytes by both HLA-B35 and HLA-A1 molecules

Antigens encoded by melanoma antigen (MAGE) genes are of particular interest for cancer immunotherapy because of their strict tumoral specificity and because they are shared by many tumors. Antigenic peptide EADPTGHSY encoded by MAGE-A1 and known to be presented by HLA-A1 is currently being used in therapeutic vaccination trials. We report here that a cytotoxic T-lymphocyte (CTL) clone, which is restricted by HLA-B35, recognizes the same peptide and, importantly, lyses HLA-B35 tumor cells expressing MAGE-A1. This peptide can be presented to CTL by both HLA-B*3501 and HLA-B*3503 molecules, which are expressed by approximately 19% of Caucasians. These results infer that the current clinical use of peptide EADPTGHSY can now be extended to HLA-B35 patients.