title: Evolution of nonclassical MHC-dependent invariant T cells.
abstract: TCR-mediated specific recognition of antigenic peptides in the context of classical MHC molecules is a cornerstone of adaptive immunity of jawed vertebrate. Ancillary to these interactions, the T cell repertoire also includes unconventional T cells that recognize endogenous and/or exogenous antigens in a classical MHC-unrestricted manner. Among these, the mammalian nonclassical MHC class I-restricted invariant T cell (iT) subsets, such as iNKT and MAIT cells, are now believed to be integral to immune response initiation as well as in orchestrating subsequent adaptive immunity. Until recently the evolutionary origins of these cells were unknown. Here we review our current understanding of a nonclassical MHC class I-restricted iT cell population in the amphibian Xenopus laevis. Parallels with the mammalian iNKT and MAIT cells underline the crucial biological roles of these evolutionarily ancient immune subsets.
authors.affiliation: Department of Microbiology and Immunology, University of Rochester Medical Center, Rochester, NY, 14642, USA.
authors.forename: Eva-Stina
authors.initials: ES
authors.lastname: Edholm
authors.forename: Leon
authors.initials: L
authors.lastname: Grayfer
authors.forename: Jacques
authors.initials: J
authors.lastname: Robert
mesh_terms: D056704:Adaptive Immunity / Q000276:immunology; D000818:Animals; D017951:Antigen Presentation / Q000276:immunology; D005075:Biological Evolution; D015395:Histocompatibility Antigens Class I / Q000276:immunology*; D018448:Models, Immunological; D055611:Natural Killer T-Cells / Q000276:immunology*; D011948:Receptors, Antigen, T-Cell / Q000276:immunology; D016176:T-Lymphocyte Subsets / Q000276:immunology; D014982:Xenopus laevis / Q000276:immunology*
chemical_list: D015395:Histocompatibility Antigens Class I; D011948:Receptors, Antigen, T-Cell