title: Expressed Salmonella antigens within macrophages enhance the proliferation of CD4+ and CD8+ T lymphocytes by means of bystander dendritic cells.
abstract: ATP-dependent Lon protease-deficient Salmonella enterica serovar Typhimurium (strain CS2022) appeared to invade successfully the mesenteric lymph nodes (MLN) and Peyer's patches (PP) of BALB/c mice and appeared to be easily eradicated by the host after oral immunization. As detected by flow cytometry, the population of major histocompatibility complex class I (MHC-I)-expressing macrophages and dendritic cells (DCs) was increased in the PP of mice immunized with CS2022 on day 6 after immunization. Thereafter, the population of splenic surface CD69(+) T lymphocytes prepared from mice immunized with CS2022 6 weeks prior to measurement increased as a result of the administration of the extracellular vesicles of RAW264.7 macrophage-like cells derived by Salmonella challenge. In addition, the proliferation of CD8(+) and even of CD4(+)T cells isolated from mouse spleens immunized with CS2022 was enhanced after cocultivation with naive DCs in the presence of the extracellular vesicles. These findings indicate that the extracellular vesicles prepared from the Salmonella-challenged macrophages carried salmonellae antigens to bystander DCs, thereby stimulating T-cell responses. Therefore, as antigen presentation after phagocytosis should be a central process in the T-cell activation that occurs in response to Salmonella infection, an oral immunization with CS2022 sufficiently induces T cell-mediated immunity in mice.
authors.affiliation: Kitasato Institute for Life Sciences and Graduate School of Infection Control Sciences, Kitasato University, Tokyo, Japan.
authors.forename: Masahiro
authors.initials: M
authors.lastname: Eguchi
authors.forename: Yukie
authors.initials: Y
authors.lastname: Sekiya
authors.forename: Yuji
authors.initials: Y
authors.lastname: Kikuchi
authors.forename: Akiko
authors.initials: A
authors.lastname: Takaya
authors.forename: Tomoko
authors.initials: T
authors.lastname: Yamamoto
authors.forename: Hidenori
authors.initials: H
authors.lastname: Matsui
mesh_terms: D000818:Animals; D017951:Antigen Presentation; D000942:Antigens, Bacterial / Q000276:immunology*; D015703:Antigens, CD / Q000032:analysis; D000945:Antigens, Differentiation, T-Lymphocyte / Q000032:analysis; D015496:CD4-Positive T-Lymphocytes / Q000276:immunology*; D018414:CD8-Positive T-Lymphocytes / Q000276:immunology*; D003713:Dendritic Cells / Q000276:immunology*; D005260:Female; D015395:Histocompatibility Antigens Class I / Q000276:immunology; D007114:Immunization; D037181:Lectins, C-Type; D008198:Lymph Nodes / Q000276:immunology; D008213:Lymphocyte Activation; D008264:Macrophages / Q000276:immunology / Q000382:microbiology; D008643:Mesentery / Q000276:immunology; D051379:Mice; D008807:Mice, Inbred BALB C; D010581:Peyer's Patches / Q000276:immunology / Q000382:microbiology; D012480:Salmonella Infections / Q000276:immunology*; D012486:Salmonella typhimurium; D013154:Spleen / Q000276:immunology; D000099192:CD69 Antigens
chemical_list: D000942:Antigens, Bacterial; D015703:Antigens, CD; D000945:Antigens, Differentiation, T-Lymphocyte; D015395:Histocompatibility Antigens Class I; D037181:Lectins, C-Type; D000099192:CD69 Antigens