A single autoimmune T cell receptor recognizes more than a million different peptides

Wooldridge, Linda, Ekeruche-Makinde, Julia, van den Berg, Hugo A., Skowera, Anna, Miles, John J., Tan, Mai Ping, Dolton, Garry, Clement, Mathew, Llewellyn-Lacey, Sian, Price, David A., Peakman, Mark, and Sewell, Andrew K. (2012) A single autoimmune T cell receptor recognizes more than a million different peptides. Journal of Biological Chemistry, 287 (2). pp. 1168-1177.

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The T cell receptor (TCR) orchestrates immune responses by binding to foreign peptides presented at the cell surface in the context of major histocompatibility complex (MHC) molecules. Effective immunity requires that all possible foreign peptide-MHC molecules are recognized or risks leaving holes in immune coverage that pathogens could quickly evolve to exploit. It is unclear how a limited pool of <10⁸ human TCRs can successfully provide immunity to the vast array of possible different peptides that could be produced from 20 proteogenic amino acids and presented by self-MHC molecules (>10¹⁵ distinct peptide-MHCs). One possibility is that T cell immunity incorporates an extremely high level of receptor degeneracy, enabling each TCR to recognize multiple peptides. However, the extent of such TCR degeneracy has never been fully quantified. Here, we perform a comprehensive experimental and mathematical analysis to reveal that a single patient-derived autoimmune CD8⁺ T cell clone of pathogenic relevance in human type I diabetes recognizes >one million distinct decamer peptides in the context of a single MHC class I molecule. A large number of peptides that acted as substantially better agonists than the wild-type "index" preproinsulin-derived peptide (ALWGPDPAAA) were identified. The RQFGPDFPTI peptide (sampled from >10⁸ peptides) was >100-fold more potent than the index peptide despite differing from this sequence at 7 of 10 positions. Quantification of this previously unappreciated high level of CD8⁺ T cell cross-reactivity represents an important step toward understanding the system requirements for adaptive immunity and highlights the enormous potential of TCR degeneracy to be the causative factor in autoimmune disease.

Item ID: 45198
Item Type: Article (Research - C1)
ISSN: 1083-351X
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© 2012 by The American Society for Biochemistry and Molecular Biology, Inc.

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Funders: Biotechnology and Biological Sciences Research Council (BBSRC), UK Department of Health (UKDH), National Institute for Health Research (NIHR)
Projects and Grants: BBSRC BB/H001085/1
Date Deposited: 23 Aug 2016 02:51
FoR Codes: 11 MEDICAL AND HEALTH SCIENCES > 1107 Immunology > 110702 Applied Immunology (incl Antibody Engineering, Xenotransplantation and T-cell Therapies) @ 100%
SEO Codes: 92 HEALTH > 9201 Clinical Health (Organs, Diseases and Abnormal Conditions) > 920108 Immune System and Allergy @ 100%
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