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Structural basis for ineffective T-cell responses to MHC anchor residue-improved 'heteroclitic' peptides.
- Source :
- European Journal of Immunology; Feb2015, Vol. 45 Issue 2, p584-591, 8p
- Publication Year :
- 2015
-
Abstract
- MHC anchor residue-modified 'heteroclitic' peptides have been used in many cancer vaccine trials and often induce greater immune responses than the wild-type peptide. The best-studied system to date is the decamer MART-1/Melan-A<subscript>26-35</subscript> peptide, EAAGIGILTV, where the natural alanine at position 2 has been modified to leucine to improve human leukocyte antigen (HLA)-A*0201 anchoring. The resulting E LAGIGILTV peptide has been used in many studies. We recently showed that T cells primed with the E LAGIGILTV peptide can fail to recognize the natural tumor-expressed peptide efficiently, thereby providing a potential molecular reason for why clinical trials of this peptide have been unsuccessful. Here, we solved the structure of a TCR in complex with HLA-A*0201-EAAGIGILTV peptide and compared it with its heteroclitic counterpart , HLA-A*0201-E LAGIGILTV. The data demonstrate that a suboptimal anchor residue at position 2 enables the TCR to 'pull' the peptide away from the MHC binding groove, facilitating extra contacts with both the peptide and MHC surface. These data explain how a TCR can distinguish between two epitopes that differ by only a single MHC anchor residue and demonstrate how weak MHC anchoring can enable an induced-fit interaction with the TCR. Our findings constitute a novel demonstration of the extreme sensitivity of the TCR to minor alterations in peptide conformation. [ABSTRACT FROM AUTHOR]
Details
- Language :
- English
- ISSN :
- 00142980
- Volume :
- 45
- Issue :
- 2
- Database :
- Complementary Index
- Journal :
- European Journal of Immunology
- Publication Type :
- Academic Journal
- Accession number :
- 100883565
- Full Text :
- https://doi.org/10.1002/eji.201445114