title: Peptide:MHC tetramer-based enrichment of epitope-specific T cells.
abstract: A basic necessity for researchers studying adaptive immunity with in vivo experimental models is an ability to identify T cells based on their T cell antigen receptor (TCR) specificity. Many indirect methods are available in which a bulk population of T cells is stimulated in vitro with a specific antigen and epitope-specific T cells are identified through the measurement of a functional response such as proliferation, cytokine production, or expression of activation markers(1). However, these methods only identify epitope-specific T cells exhibiting one of many possible functions, and they are not sensitive enough to detect epitope-specific T cells at naive precursor frequencies. A popular alternative is the TCR transgenic adoptive transfer model, in which monoclonal T cells from a TCR transgenic mouse are seeded into histocompatible hosts to create a large precursor population of epitope-specific T cells that can be easily tracked with the use of a congenic marker antibody(2,3). While powerful, this method suffers from experimental artifacts associated with the unphysiological frequency of T cells with specificity for a single epitope(4,5). Moreover, this system cannot be used to investigate the functional heterogeneity of epitope-specific T cell clones within a polyclonal population. The ideal way to study adaptive immunity should involve the direct detection of epitope-specific T cells from the endogenous T cell repertoire using a method that distinguishes TCR specificity solely by its binding to cognate peptide:MHC (pMHC) complexes. The use of pMHC tetramers and flow cytometry accomplishes this(6), but is limited to the detection of high frequency populations of epitope-specific T cells only found following antigen-induced clonal expansion. In this protocol, we describe a method that coordinates the use of pMHC tetramers and magnetic cell enrichment technology to enable detection of extremely low frequency epitope-specific T cells from mouse lymphoid tissues(3,7). With this technique, one can comprehensively track entire epitope-specific populations of endogenous T cells in mice at all stages of the immune response.
authors.affiliation: Center for Immunology and Inflammatory Diseases, and Pulmonary and Critical Care Unit, Massachusetts General Hospital and Harvard Medical School, USA.
authors.forename: Francois P
authors.initials: FP
authors.lastname: Legoux
authors.forename: James J
authors.initials: JJ
authors.lastname: Moon
mesh_terms: D056704:Adaptive Immunity / Q000276:immunology; D000818:Animals; D018604:Epitope Mapping / Q000379:methods; D018984:Epitopes, T-Lymphocyte / Q000276:immunology*; D005434:Flow Cytometry / Q000379:methods; D008280:Magnetics / Q000379:methods; D008285:Major Histocompatibility Complex / Q000276:immunology*; D051379:Mice; D008822:Mice, Transgenic; D010455:Peptides / Q000276:immunology*; D011948:Receptors, Antigen, T-Cell / Q000276:immunology; D013601:T-Lymphocytes / Q000166:cytology / Q000276:immunology*
chemical_list: D018984:Epitopes, T-Lymphocyte; D010455:Peptides; D011948:Receptors, Antigen, T-Cell