Valmori D, Fonteneau J F, Lizana C M, Gervois N, Liénard D, Rimoldi D, Jongeneel V, Jotereau F, Cerottini J C, Romero P
Division of Clinical Onco-Immunology, Ludwig Institute for Cancer Research, Lausanne, Switzerland.
J Immunol. 1998 Feb 15;160(4):1750-8.
The Melan-A/MART-1 gene, which is expressed by normal melanocytes as well as by most fresh melanoma samples and melanoma cell lines, codes for Ags recognized by tumor-reactive CTL. HLA-A0201-restricted Melan-A-specific CTL recognize primarily the Melan-A(27-35) (AAGIGILTV) and the Melan-A(26-35) (EAAGIGILTV) peptides. The sequences of these two peptides are not necessarily optimal as far as binding to HLA-A0201 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-A0201 and/or recognition by specific CTL. Surprisingly, analogues of the Melan-A(27-35) peptide, which bound more efficiently than the natural nonapeptide to HLA-A0201, were poorly recognized by tumor-reactive CTL. In contrast, among the Melan-A(26-35) 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 of five tumor-reactive CTL clones. Moreover, in vitro generation of tumor-reactive CTL by stimulation of PBMC from HLA-A0201 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-A(26-35) peptide analogue ELAGIGILTV may be more immunogenic than the natural peptides in HLA-A0201 melanoma patients and should thus be considered as a candidate for future peptide-based vaccine trials.
Melan-A/MART-1基因由正常黑素细胞以及大多数新鲜黑色素瘤样本和黑色素瘤细胞系表达，编码可被肿瘤反应性CTL识别的抗原。HLA-A0201限制性Melan-A特异性CTL主要识别Melan-A(27 - 35)（AAGIGILTV）和Melan-A(26 - 35)（EAAGIGILTV）肽段。就与HLA-A0201的结合而言，这两个肽段的序列不一定是最优的，因为两者在第2位都缺少一个主要的锚定氨基酸残基（亮氨酸或甲硫氨酸）。在本研究中，我们在这两个天然肽段序列中的任意一个引入单个氨基酸替换，目的是改善肽段与HLA-A0201的结合和/或被特异性CTL识别的能力。令人惊讶的是，Melan-A(27 - 35)肽段的类似物虽然比天然九肽更有效地结合HLA-A0201，但却很难被肿瘤反应性CTL识别。相反，在测试的Melan-A(26 - 35)肽段类似物中，肽段ELAGIGILTV不仅能够与HLA-A2.1稳定结合，而且被两个短期培养的肿瘤浸润淋巴结细胞培养物以及五个肿瘤反应性CTL克隆中的五个比天然肽段更有效地识别。此外，用这种特定的肽段类似物刺激HLA-A0201黑色素瘤患者的PBMC在体外产生肿瘤反应性CTL比用这两种天然肽段中的任何一种观察到的效率都要高得多。这些结果表明，Melan-A(26 - 35)肽段类似物ELAGIGILTV在HLA-A0201黑色素瘤患者中可能比天然肽段更具免疫原性，因此应被视为未来基于肽段的疫苗试验的候选物。
