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

Linda Wooldridge, Julia Ekeruche-Makinde, Hugo A van den Berg, Anna Skowera, John J Miles, Mai Ping Tan, Garry Dolton, Mathew Clement, Sian Llewellyn-Lacey, David A Price, Mark Peakman, Andrew K Sewell

Research output: Contribution to journalArticle (Academic Journal)peer-review

322 Citations (Scopus)


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 10(15) 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 >10(8) 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.
Original languageEnglish
Pages (from-to)1168-1177
Number of pages10
JournalJournal of Biological Chemistry
Issue number2
Early online date18 Nov 2011
Publication statusPublished - 6 Jan 2012


  • HLA-A2 Antigen
  • Models, Immunological
  • Diabetes Mellitus, Type 1
  • Humans
  • CD8-Positive T-Lymphocytes
  • Receptors, Antigen, T-Cell
  • Autoimmunity
  • Protein Precursors
  • Peptides
  • Insulin


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