title: Epitope selection in major histocompatibility complex class I-mediated pathway is affected by the intracellular localization of an antigen.
abstract: We analyzed the mode of antigen presentation of an endogenous antigen localized in the cytoplasm or in the mitochondria. Pseudomonas aeruginosa PAO leucine-, isoleucine-, valine-binding protein (LIVAT-BP) encoded by the braC gene was used as a model antigen. Using mouse BALB/3T3 cells, we established two LIVAT-BP transfectants by transfection of a plasmid harboring the intact braC or braC gene fused with the mitochondrial transport signal derived from the yeast COXIV gene. One of the resulting transfectants, BC-15, expressed LIVAT-BP in the cytoplasm, while YZ-710 cells expressed LIVAT-BP in the mitochondria. The splenic effector cells derived from BALB/c mice primed with BC-15 cells exhibited cytotoxic T lymphocyte (CTL) activity against BC-15 cells, but not against YZ-710 cells, whereas splenic effector cells primed with YZ-710 cells exhibited CTL activity against YZ-710 cells, but not against BC-15 cells. Neither group of splenic effector cells showed CTL activity against parental BALB/3T3 cells. These CTL belonged to the CD8+ alphabeta T cell subset. Furthermore, we observed that the CTL activity against t BC-15 cells or YZ-710 cells was blocked with anti-H2-K(d) mAb, but not with anti-H2-D(d) or H2-L(d) mAb. The CTL against BC-15 or YZ-710 cells could kill parental BALB/3T3 cells in the presence of peptides produced by alkali lysis of the LIVAT-BP, suggesting that these CTL indeed recognized the peptide(s) derived from LIVAT-BP. We determined that the epitope for the CTL against BC-15 cells was QYGEGIATEV, corresponding to residues 162-171, and that the epitope recognized by the CTL against YZ-710 cells was GYKLIFRTI, corresponding to residues 123-131 of LIVAT-BP, respectively. Thus, we show here that epitope selection for MHC class I expression is affected by the intracellular localization of the antigenic protein.
authors.affiliation: Department of Immunology and Parasitology, Yokohama City University School of Medicine, Japan.
authors.forename: H
authors.initials: H
authors.lastname: Yamazaki
authors.forename: M
authors.initials: M
authors.lastname: Tanaka
authors.forename: M
authors.initials: M
authors.lastname: Nagoya
authors.forename: H
authors.initials: H
authors.lastname: Fujimaki
authors.forename: K
authors.initials: K
authors.lastname: Sato
authors.forename: T
authors.initials: T
authors.lastname: Yago
authors.forename: T
authors.initials: T
authors.lastname: Nagata
authors.forename: M
authors.initials: M
authors.lastname: Minami
mesh_terms: D016475:3T3 Cells; D000595:Amino Acid Sequence; D000818:Animals; D017951:Antigen Presentation / Q000276:immunology*; D001426:Bacterial Proteins; D002352:Carrier Proteins / Q000276:immunology*; D003593:Cytoplasm / Q000648:ultrastructure; D000939:Epitopes / Q000276:immunology*; D005260:Female; D006183:H-2 Antigens / Q000235:genetics*; D051379:Mice; D008807:Mice, Inbred BALB C; D008928:Mitochondria / Q000648:ultrastructure; D008969:Molecular Sequence Data; D013602:T-Lymphocytes, Cytotoxic / Q000276:immunology / Q000648:ultrastructure*; D014162:Transfection / Q000235:genetics
chemical_list: D001426:Bacterial Proteins; D002352:Carrier Proteins; D000939:Epitopes; D006183:H-2 Antigens; C035178:LIVAT-BP protein, Pseudomonas aeruginosa