title: Optimized tetramer analysis reveals Ly49 promiscuity for MHC ligands.
abstract: Murine Ly49 receptors, which are expressed mainly on NK and NKT cells, interact with MHC class I (MHC-I) molecules with varying specificity. Differing reports of Ly49/MHC binding affinities may be affected by multiple factors, including cis versus trans competition and species origin of the MHC-I L chain (β2-microglobulin). To determine the contribution of each of these factors, Ly49G, Ly49I, Ly49O, Ly49V, and Ly49Q receptors from the 129 mouse strain were expressed individually on human 293T cells or the mouse cell lines MHC-I-deficient C1498, H-2(b)-expressing MC57G, and H-2(k)-expressing L929. The capacity to bind to H-2D(b)- and H-2K(b)-soluble MHC-I tetramers containing either human or murine β2-microglobulin L chains was tested for all five Ly49 receptors in all four cell lines. We found that most of these five inhibitory Ly49 receptors show binding for one or both self-MHC-I molecules in soluble tetramer binding assays when three conditions are fulfilled: 1) lack of competing cis interactions, 2) tetramer L chain is of mouse origin, and 3) Ly49 is expressed in mouse and not human cell lines. Furthermore, Ly49Q, the single known MHC-I receptor on plasmacytoid dendritic cells, was shown to bind H-2D(b) in addition to H-2K(b) when the above conditions were met, suggesting that Ly49Q functions as a pan-MHC-Ia receptor on plasmacytoid dendritic cells. In this study, we have optimized the parameters for soluble tetramer binding analyses to enhance future Ly49 ligand identification and to better evaluate specific contributions by different Ly49/MHC-I pairs to NK cell education and function.
authors.affiliation: Department of Biochemistry, Microbiology, and Immunology, University of Ottawa, Ottawa, Ontario K1H 8M5, Canada;
authors.forename: Emily
authors.initials: E
authors.lastname: McFall
authors.forename: Megan M
authors.initials: MM
authors.lastname: Tu
authors.forename: Nuha
authors.initials: N
authors.lastname: Al-Khattabi
authors.forename: Lee-Hwa
authors.initials: LH
authors.lastname: Tai
authors.forename: Aaron S
authors.initials: AS
authors.lastname: St-Laurent
authors.forename: Velina
authors.initials: V
authors.lastname: Tzankova
authors.forename: Clayton W
authors.initials: CW
authors.lastname: Hall
authors.forename: Simon
authors.initials: S
authors.lastname: Belanger
authors.forename: Angela D
authors.initials: AD
authors.lastname: Troke
authors.forename: Andrew
authors.initials: A
authors.lastname: Wight
authors.forename: Ahmad Bakur
authors.initials: AB
authors.lastname: Mahmoud
authors.forename: Haggag S
authors.initials: HS
authors.lastname: Zein
authors.forename: Mir Munir A
authors.initials: MM
authors.lastname: Rahim
authors.forename: James R
authors.initials: JR
authors.lastname: Carlyle
authors.forename: Andrew P
authors.initials: AP
authors.lastname: Makrigiannis
mesh_terms: D000818:Animals; D002454:Cell Differentiation; D002469:Cell Separation; D003601:Cytotoxicity Tests, Immunologic; D003713:Dendritic Cells / Q000276:immunology*; D005434:Flow Cytometry / Q000379:methods; D057809:HEK293 Cells; D015395:Histocompatibility Antigens Class I / Q000235:genetics / Q000276:immunology / Q000378:metabolism*; D006801:Humans; D007694:Killer Cells, Natural / Q000276:immunology*; D008024:Ligands; D051379:Mice; D018345:Mice, Knockout; D055650:NK Cell Lectin-Like Receptor Subfamily A / Q000235:genetics / Q000276:immunology / Q000378:metabolism*; D055611:Natural Killer T-Cells / Q000276:immunology*; D011485:Protein Binding; D015202:Protein Engineering; D013045:Species Specificity
chemical_list: D015395:Histocompatibility Antigens Class I; D008024:Ligands; D055650:NK Cell Lectin-Like Receptor Subfamily A