title: The majority of H2-M3 is retained intracellularly in a peptide-receptive state and traffics to the cell surface in the presence of N-formylated peptides.
abstract: We used a new monoclonal antibody (mAb 130) to analyze the intracellular trafficking and surface expression of H2-M3, the major histocompatibility complex class Ib molecule that presents N-formylated peptides to cytotoxic T cells. M3 surface expression is undetectable in most cell types due to the paucity of endogenous antigen. M3 is induced on the cell surface by addition of high-affinity N-formylated peptides from mitochondria and listeria. Peptide-induced M3 expression is most efficient on antigen presenting cells. Basal and inducible expression of M3 is transporter associated with antigen processing (TAP)-dependent, distinguishing M3 from the class Ib molecules TL and CD1. Unlike the expression of class Ia molecules and a previously described M3/L(d) chimera, surface expression of M3 cannot be rescued by lowered temperature, suggesting that the alpha3 domain and transmembrane region of M3 may control trafficking. Pulse-chase analysis and use of trafficking inhibitors revealed a pool of empty M3 in the endoplasmic reticulum or early Golgi apparatus. Addition of exogenous peptide allows maturation with kinetics matching those of D(d). The lack of endogenous N-formylated peptide allows discovery of novel pathogen-derived peptides in normal antigen presenting cells. The nonpolymorphic nature of M3 and its ability to present bacterial antigens rapidly and dominantly make it an attractive target for peptide vaccination strategies.
authors.affiliation: Gwen Knapp Center for Lupus and Immunology Research, Committee on Immunology, Department of Pathology, University of Chicago, Illinois 60637, USA.
authors.forename: N M
authors.initials: NM
authors.lastname: Chiu
authors.forename: T
authors.initials: T
authors.lastname: Chun
authors.forename: M
authors.initials: M
authors.lastname: Fay
authors.forename: M
authors.initials: M
authors.lastname: Mandal
authors.forename: C R
authors.initials: CR
authors.lastname: Wang
mesh_terms: D000071181:ATP Binding Cassette Transporter, Subfamily B, Member 2; D018528:ATP-Binding Cassette Transporters / Q000494:pharmacology; D000818:Animals; D000911:Antibodies, Monoclonal / Q000096:biosynthesis / Q000494:pharmacology; D017951:Antigen Presentation / Q000187:drug effects; D001692:Biological Transport / Q000276:immunology; D002460:Cell Line; D002462:Cell Membrane / Q000276:immunology / Q000378:metabolism; D006224:Cricetinae; D015395:Histocompatibility Antigens Class I / Q000096:biosynthesis / Q000276:immunology / Q000378:metabolism*; D007424:Intracellular Fluid / Q000276:immunology / Q000378:metabolism*; D007700:Kinetics; D008221:Lymphoid Tissue / Q000166:cytology / Q000276:immunology / Q000378:metabolism; D008565:Membrane Proteins / Q000096:biosynthesis / Q000276:immunology / Q000378:metabolism*; D051379:Mice; D008810:Mice, Inbred C57BL; D009239:N-Formylmethionine / Q000378:metabolism*; D009842:Oligopeptides / Q000276:immunology / Q000378:metabolism* / Q000502:physiology; D011500:Protein Synthesis Inhibitors / Q000494:pharmacology
chemical_list: D000071181:ATP Binding Cassette Transporter, Subfamily B, Member 2; D018528:ATP-Binding Cassette Transporters; D000911:Antibodies, Monoclonal; C078177:H2-M3 antigen; D015395:Histocompatibility Antigens Class I; D008565:Membrane Proteins; D009842:Oligopeptides; D011500:Protein Synthesis Inhibitors; C073119:TAP1 protein, human; C486171:Tap1 protein, mouse; D009239:N-Formylmethionine