title: H2-M mutant mice are defective in the peptide loading of class II molecules, antigen presentation, and T cell repertoire selection.
abstract: H2-M is a nonconventional major histocompatibility complex (MHC) class II molecule that has been implicated in the loading of peptides onto conventional class II molecules. We generated mice with a targeted mutation in the H2-Ma gene, which encodes a subunit for H2-M. Although the mutant mice express normal class II cell surface levels, these are structurally distinct from the compact SDS-resistant complexes expressed by wild-type cells and are predominantly bound by class II-associated invariant chain peptides (CLIPs). Cells from these animals are unable to present intact protein antigens to class II-restricted T cells and show reduced capacity to present exogenous peptides. Numbers of mature CD4+ T lymphocytes in mutant mice are reduced 3- to 4-fold and exhibit altered reactivities. Overall, this phenotype establishes an important role for H2-M in regulating MHC class II function in vivo and supports the notion that self-peptides contribute to the specificity of T cell positive selection.
authors.affiliation: Howard Hughes Medical Institute, Department of Microbiology and Immunology, Vanderbilt University School of Medicine, Nashville, Tennessee 37232, USA.
authors.forename: W D
authors.initials: WD
authors.lastname: Martin
authors.forename: G G
authors.initials: GG
authors.lastname: Hicks
authors.forename: S K
authors.initials: SK
authors.lastname: Mendiratta
authors.forename: H I
authors.initials: HI
authors.lastname: Leva
authors.forename: H E
authors.initials: HE
authors.lastname: Ruley
authors.forename: L
authors.initials: L
authors.lastname: Van Kaer
mesh_terms: D000818:Animals; D017951:Antigen Presentation / Q000276:immunology*; D000944:Antigens, Differentiation, B-Lymphocyte / Q000276:immunology / Q000378:metabolism; D001692:Biological Transport / Q000276:immunology; D015496:CD4-Positive T-Lymphocytes / Q000166:cytology / Q000276:immunology / Q000378:metabolism; D018414:CD8-Positive T-Lymphocytes / Q000166:cytology; D015870:Gene Expression / Q000276:immunology; D000949:Histocompatibility Antigens Class II / Q000235:genetics* / Q000276:immunology / Q000378:metabolism; D018655:Lymphocyte Count; D008565:Membrane Proteins / Q000276:immunology; D051379:Mice; D008817:Mice, Mutant Strains; D010455:Peptides / Q000276:immunology / Q000378:metabolism; D010641:Phenotype; D011485:Protein Binding / Q000276:immunology; D013154:Spleen / Q000166:cytology; D013601:T-Lymphocytes / Q000276:immunology* / Q000378:metabolism / Q000648:ultrastructure
chemical_list: D000944:Antigens, Differentiation, B-Lymphocyte; D000949:Histocompatibility Antigens Class II; D008565:Membrane Proteins; D010455:Peptides; C045084:invariant chain