Enhanced generation of specific tumor-reactive CTL in vitro by selected Melan-A/MART-1 immunodominant peptide analogues

Danila Valmori, Jean François Fonteneau, Concepción Marañón Lizana, Nadine Gervois, Danielle Liénard, Donata Rimoldi, Victor Jongeneel, Francine Jotereau, Jean Charles Cerottini, Pedro Romero

Research output: Contribution to journalArticlepeer-review

Abstract

The Melan-A/MART-1 gene, which is expressed by normal melanocytes as well as most fresh melanoma samples and melanoma cell lines, codes for Ags recognized by tumor-reactive CTL. HLA-A*0201-restricted Melan-A-specific CTL recognize primarily the Melan-A27-35 (AAGIGILTV) and the Melan-A26- 35 (EAAGIGILTV) peptides. The sequences of these two peptides are not necessarily optimal as far as binding to HLA-A*,0201 is concerned, since both lack one of the dominant anchor amino acid residues (leucine or methionine) at position 2. In this study we introduced single amino acid substitutions in either one of the two natural peptide sequences with the aim of improving peptide binding to HLA-A*,0201 and/or recognition by specific CTL. Surprisingly, analogues of the Melan-A27-35 peptide, which bound more efficiently than the natural nonapeptide to HLA-A*,0201, were poorly recognized by tumor-reactive CTL. In contrast, among the Melan-A26-35 peptide analogues tested, the peptide ELAGIGILTV was not only able to display stable binding to HLA-A2.1 but was also recognized more efficiently than the natural peptide by two short-term cultured tumor-infiltrated lymph node cell cultures as well as by five tumor-reactive CTL clones. Moreover, in vitro generation of tumor-reactive CTL by stimulation of PBMC from HLA-A*,0201 melanoma patients with this particular peptide analogue was much more efficient than that observed with either one of the two natural peptides. These results suggest that the Melan-A26-35 peptide analogue ELAGIGILTV may be more immunogenic than the natural peptides in HLA-A*,0201 melanoma patients and should thus be considered as a candidate for future peptide- based vaccine trials.

Original languageEnglish (US)
Pages (from-to)1750-1758
Number of pages9
JournalJournal of Immunology
Volume160
Issue number4
StatePublished - Feb 15 1998

ASJC Scopus subject areas

  • Immunology

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