title: CD1d protein structure determines species-selective antigenicity of isoglobotrihexosylceramide (iGb3) to invariant NKT cells.
abstract: Isoglobotrihexosylceramide (iGb3) has been identified as a potent CD1d-presented self-antigen for mouse invariant natural killer T (iNKT) cells. The role of iGb3 in humans remains unresolved, however, as there have been conflicting reports about iGb3-dependent human iNKT-cell activation, and humans lack iGb3 synthase, a key enzyme for iGb3 synthesis. Given the importance of human immune responses, we conducted a human-mouse cross-species analysis of iNKT-cell activation by iGb3-CD1d. Here we show that human and mouse iNKT cells were both able to recognise iGb3 presented by mouse CD1d (mCD1d), but not human CD1d (hCD1d), as iGb3-hCD1d was unable to support cognate interactions with the iNKT-cell TCRs tested in this study. The structural basis for this discrepancy was identified as a single amino acid variation between hCD1d and mCD1d, a glycine-to-tryptophan modification within the α2-helix that prevents flattening of the iGb3 headgroup upon TCR ligation. Mutation of the human residue, Trp153, to the mouse ortholog, Gly155, therefore allowed iGb3-hCD1d to stimulate human iNKT cells. In conclusion, our data indicate that iGb3 is unlikely to be a major antigen in human iNKT-cell biology.
authors.affiliation: Academic Unit of Clinical and Experimental Sciences, Faculty of Medicine, Sir Henry Wellcome and Hope Laboratories, Southampton Musculoskeletal BRU, University of Southampton, Southampton, United Kingdom.
authors.forename: Joseph P
authors.initials: JP
authors.lastname: Sanderson
authors.forename: Patrick J
authors.initials: PJ
authors.lastname: Brennan
authors.forename: Salah
authors.initials: S
authors.lastname: Mansour
authors.forename: Gediminas
authors.initials: G
authors.lastname: Matulis
authors.forename: Onisha
authors.initials: O
authors.lastname: Patel
authors.forename: Nikolai
authors.initials: N
authors.lastname: Lissin
authors.forename: Dale I
authors.initials: DI
authors.lastname: Godfrey
authors.forename: Kazuyoshi
authors.initials: K
authors.lastname: Kawahara
authors.forename: Ulrich
authors.initials: U
authors.lastname: Zähringer
authors.forename: Jamie
authors.initials: J
authors.lastname: Rossjohn
authors.forename: Michael B
authors.initials: MB
authors.lastname: Brenner
authors.forename: Stephan D
authors.initials: SD
authors.lastname: Gadola
mesh_terms: D000596:Amino Acids; D000818:Animals; D017951:Antigen Presentation; D055610:Antigens, CD1d / Q000737:chemistry / Q000276:immunology* / Q000378:metabolism; D005915:Globosides / Q000276:immunology* / Q000378:metabolism; D006801:Humans; D008213:Lymphocyte Activation / Q000276:immunology; D051379:Mice; D008958:Models, Molecular; D055611:Natural Killer T-Cells / Q000276:immunology*; D011485:Protein Binding; D011487:Protein Conformation; D054730:Protein Interaction Domains and Motifs; D011948:Receptors, Antigen, T-Cell / Q000378:metabolism; D013045:Species Specificity; D014281:Trihexosylceramides / Q000276:immunology* / Q000378:metabolism
chemical_list: D000596:Amino Acids; D055610:Antigens, CD1d; D005915:Globosides; D011948:Receptors, Antigen, T-Cell; D014281:Trihexosylceramides; C514781:isoglobotrihexosylceramide