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Nature. 2010 Apr 8;464(7290):932-6. doi: 10.1038/nature08944. Epub 2010 Mar 31.

The kinetics of two-dimensional TCR and pMHC interactions determine T-cell responsiveness.

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1
Coulter Department of Biomedical Engineering, Georgia Institute of Technology, Atlanta, Georgia 30332, USA.

Abstract

The T-cell receptor (TCR) interacts with peptide-major histocompatibility complexes (pMHC) to discriminate pathogens from self-antigens and trigger adaptive immune responses. Direct physical contact is required between the T cell and the antigen-presenting cell for cross-junctional binding where the TCR and pMHC are anchored on two-dimensional (2D) membranes of the apposing cells. Despite their 2D nature, TCR-pMHC binding kinetics have only been analysed three-dimensionally (3D) with a varying degree of correlation with the T-cell responsiveness. Here we use two mechanical assays to show high 2D affinities between a TCR and its antigenic pMHC driven by rapid on-rates. Compared to their 3D counterparts, 2D affinities and on-rates of the TCR for a panel of pMHC ligands possess far broader dynamic ranges that match that of their corresponding T-cell responses. The best 3D predictor of response is the off-rate, with agonist pMHC dissociating the slowest. In contrast, 2D off-rates are up to 8,300-fold faster, with the agonist pMHC dissociating the fastest. Our 2D data suggest rapid antigen sampling by T cells and serial engagement of a few agonist pMHCs by TCRs in a large self pMHC background. Thus, the cellular environment amplifies the intrinsic TCR-pMHC binding to generate broad affinities and rapid kinetics that determine T-cell responsiveness.

PMID:
20357766
PMCID:
PMC2925443
DOI:
10.1038/nature08944
[Indexed for MEDLINE]
Free PMC Article
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