title: In vitro evolution of a T cell receptor with high affinity for peptide/MHC.
abstract: T cell receptors (TCRs) exhibit genetic and structural diversity similar to antibodies, but they have binding affinities that are several orders of magnitude lower. It has been suggested that TCRs undergo selection in vivo to maintain lower affinities. Here, we show that there is not an inherent genetic or structural limitation on higher affinity. Higher-affinity TCR variants were generated in the absence of in vivo selective pressures by using yeast display and selection from a library of Valpha CDR3 mutants. Selected mutants had greater than 100-fold higher affinity (K(D) approximately 9 nM) for the peptide/MHC ligand while retaining a high degree of peptide specificity. Among the high-affinity TCR mutants, a strong preference was found for CDR3alpha that contained Pro or Gly residues. Finally, unlike the wild-type TCR, a soluble monomeric form of a high-affinity TCR was capable of directly detecting peptide/MHC complexes on antigen-presenting cells. These findings prove that affinity maturation of TCRs is possible and suggest a strategy for engineering TCRs that can be used in targeting specific peptide/MHC complexes for diagnostic and therapeutic purposes.
authors.affiliation: Department of Biochemistry, University of Illinois, Urbana, IL 61801, USA.
authors.forename: P D
authors.initials: PD
authors.lastname: Holler
authors.forename: P O
authors.initials: PO
authors.lastname: Holman
authors.forename: E V
authors.initials: EV
authors.lastname: Shusta
authors.forename: S
authors.initials: S
authors.lastname: O'Herrin
authors.forename: K D
authors.initials: KD
authors.lastname: Wittrup
authors.forename: D M
authors.initials: DM
authors.lastname: Kranz
mesh_terms: D000595:Amino Acid Sequence; D019943:Amino Acid Substitution; D000818:Animals; D001483:Base Sequence; D017931:DNA Primers; D019281:Dimerization; D019020:Directed Molecular Evolution / Q000379:methods*; D015723:Gene Library; D014644:Genetic Variation; D005998:Glycine; D008024:Ligands; D008285:Major Histocompatibility Complex; D008958:Models, Molecular; D008969:Molecular Sequence Data; D016297:Mutagenesis, Site-Directed; D011392:Proline; D011487:Protein Conformation; D017260:Receptor-CD3 Complex, Antigen, T-Cell / Q000737:chemistry / Q000235:genetics / Q000276:immunology*; D011948:Receptors, Antigen, T-Cell / Q000737:chemistry* / Q000235:genetics / Q000276:immunology*; D016693:Receptors, Antigen, T-Cell, alpha-beta / Q000235:genetics / Q000276:immunology; D011994:Recombinant Proteins / Q000737:chemistry / Q000276:immunology
chemical_list: D017931:DNA Primers; D008024:Ligands; D017260:Receptor-CD3 Complex, Antigen, T-Cell; D011948:Receptors, Antigen, T-Cell; D016693:Receptors, Antigen, T-Cell, alpha-beta; D011994:Recombinant Proteins; D011392:Proline; D005998:Glycine