The large majority of known melanoma-associated antigenic peptides presented by MHC class I molecules are presented by the most frequent allele, HLA-A*0201. Thus although a significant percentage of Caucasians express HLA-A3, no melanoma-associated antigenic peptide presented by this allele has yet been identified. We show here that the T cell clone M45-10 isolated from tumor infiltrating lymphocytes recovered from a melanoma biopsy recognizes the gp100-derived peptide ALLAVGATK presented by HLA-A*0301. Since gp100 is expressed on most melanoma cells, our results imply that the gp100-based anti-melanoma strategies developed for individuals expressing HLA-A2 will also be applicable to those expressing HLA-AS (about one Caucasian in four). gp100 is therefore a particularly promising melanoma antigen, as different peptides derived from it can be presented by at least two different frequently encountered HLA class I molecules.

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