MULTIPLE HLA-A ALLELES CAN PRESENT AN IMMUNODOMINANT PEPTIDE OF THE HUMAN-MELANOMA ANTIGEN MELAN-A MART-1 TO A PEPTIDE-SPECIFIC HLA-A-ASTERISK-0201(+) CYTOTOXIC T-CELL LINE/

The majority of HLA-A0201-restricted tumor-infiltrating lymphocytes f rom melanoma patients recognize a peptide, MT(27-35), derived from the Melan-A/MART-1 Ag. This study reports that six variants of HLA-A2 and the HLA-A28 subtype A6901 can present peptide MT(27-35). A CTL line specific for peptide MT(27-35) was generated by in vitro stimulation o f PBL of an HLA-A0201(+), healthy donor with peptide-pulsed, activate d autologous B lymphoblasts. This CTL line was shown to recognize pept ide MT(27-35) after endogenous processing on Melan-A/MART-1(+)/HLA-A2( +) tumor cells. Moreover, a panel of B lymphoblastoid cell lines (BLCL s) expressing A0202, A*0204, A*0205, A*0206, A*0209, and with lower e fficiency A6901, could be sensitized to lysis upon incubation with th e relevant peptide. As demonstrated by the levels of ED(50) and CD8 de pendency of lysis, HLA-A0204 and HLA-A*0205 presented the peptide as efficiently as HLA-A0201, while the other four alleles were less effi cient. Peptide-binding studies suggest that TCR-rather than peptide-bi nding affinity determines the T cell recognition levels of peptide-pul sed EBV-BLCLs expressing A0201, A*0204, A*0206, and A*0209. Peptide-p ulsed BLCLs expressing HLA-A0207 or two additional subtypes of HLA-A2 8 were not recognized. MT(27-35)-specific CTL could also be raised fro m donors expressing HLA-A0205. These findings have implications on th e applicability of peptide vaccination with peptide MT(27-35) on melan oma patients.