title: Peptide-MHC class I tetrameric complexes display exquisite ligand specificity.
abstract: The production of synthetic MHC-peptide tetramers has revolutionized cellular immunology by revealing enormous CD8(+) T cell expansions specific for peptides from various pathogens. A feature of these reagents, essential for their staining function, is that they bind T cells with relatively high avidity. This could, theoretically, promote cross-reactivity with irrelevant T cells leading to overestimates of epitope-specific T cell numbers. Therefore, we have investigated the fine specificity of CTL staining with these reagents for comparison with functional data. Using a panel of CTL clones with distinct fine specificity patterns for analogs of an HLA-B8-binding EBV epitope, together with B8 tetramers incorporating these peptides, we show a very good correlation between tetramer staining and peptide activity in cytotoxicity assays. Significant staining only occurred with tetramers that incorporate strong stimulatory agonist peptides and not weak agonists that are unlikely to induce full T cell activation at physiological levels of presentation. In almost every case where a peptide analog had >10-fold less activity than the optimal EBV peptide in cytotoxicity assays, the corresponding tetramer stained with >10-fold less intensity than the EBV epitope tetramer. Furthermore, by examining an EBV-specific clonotypic T cell expansion in EBV-exposed individuals, we show similar fine specificity in tetramer staining of fresh peripheral T cells. Collectively, our data demonstrate the exquisite specificity of class I MHC-peptide tetramers, underlining their accuracy in quantifying only those T cells capable of recognizing the low levels of cell surface peptide presented after endogenous Ag processing.
authors.affiliation: Division of Infectious Diseases and Immunology, Queensland Institute of Medical Research and University of Queensland Joint Oncology Program, The Bancroft Centre, Brisbane, Australia. scott@qimr.edu.au
authors.forename: S R
authors.initials: SR
authors.lastname: Burrows
authors.forename: N
authors.initials: N
authors.lastname: Kienzle
authors.forename: A
authors.initials: A
authors.lastname: Winterhalter
authors.forename: M
authors.initials: M
authors.lastname: Bharadwaj
authors.forename: J D
authors.initials: JD
authors.lastname: Altman
authors.forename: A
authors.initials: A
authors.lastname: Brooks
mesh_terms: D017951:Antigen Presentation / Q000276:immunology; D000956:Antigens, Viral / Q000276:immunology / Q000378:metabolism; D002461:Cell Line, Transformed; D002999:Clone Cells / Q000737:chemistry / Q000276:immunology / Q000378:metabolism; D003601:Cytotoxicity Tests, Immunologic; D018984:Epitopes, T-Lymphocyte / Q000737:chemistry / Q000378:metabolism*; D015795:HLA-B8 Antigen / Q000737:chemistry / Q000378:metabolism*; D004854:Herpesvirus 4, Human / Q000276:immunology; D006801:Humans; D016056:Immunodominant Epitopes / Q000737:chemistry / Q000378:metabolism; D008024:Ligands; D009842:Oligopeptides / Q000737:chemistry / Q000276:immunology* / Q000378:metabolism* / Q000502:physiology; D011485:Protein Binding / Q000276:immunology; D013194:Staining and Labeling; D013602:T-Lymphocytes, Cytotoxic / Q000276:immunology / Q000378:metabolism
chemical_list: D000956:Antigens, Viral; D018984:Epitopes, T-Lymphocyte; D015795:HLA-B8 Antigen; D016056:Immunodominant Epitopes; D008024:Ligands; D009842:Oligopeptides