title: In vivo activation of dendritic cells and T cells during Salmonella enterica serovar Typhimurium infection.
abstract: The present study was initiated to gain insight into the interaction between splenic dendritic cells (DC) and Salmonella enterica serovar Typhimurium in vivo. Splenic phagocytic cell populations associated with green fluorescent protein (GFP)-expressing bacteria and the bacterium-specific T-cell response were evaluated in mice given S. enterica serovar Typhimurium expressing GFP and ovalbumin. Flow cytometry analysis revealed that GFP-positive splenic DC (CD11c+ major histocompatibility complex class II-positive [MHC-II+] cells) were present following bacterial administration, and confocal microscopy showed that GFP-expressing bacteria were contained within CD11c+ MHC-II+ splenocytes. Furthermore, splenic DC and T cells were activated following Salmonella infection. This was shown by increased surface expression of CD86 and CD40 on CD11c+ MHC-II+ cells and increased CD44 and CD69 expression on CD4+ and CD8+ T cells. Salmonella-specific gamma interferon (IFN-gamma)-producing cells in both of these T-cell subsets, as well as cytolytic effector cells, were also generated in mice given live bacteria. The frequency of Salmonella-specific CD4+ T cells producing IFN-gamma was greater than that of specific CD8+ T cells producing IFN-gamma in the same infected animal. This supports the argument that the predominant source of IFN-gamma production by cells of the specific immune response is CD4+ T cells. Finally, DC that phagocytosed live or heat-killed Salmonella in vitro primed bacterium-specific IFN-gamma-producing CD4+ and CD8+ T cells as well as cytolytic effector cells following administration into naïve mice. Together these data suggest that DC are involved in priming naïve T cells to Salmonella in vivo.
authors.affiliation: Department of Cell and Molecular Biology, Section for Immunology, Lund University, Lund, Sweden.
authors.forename: U
authors.initials: U
authors.lastname: Yrlid
authors.forename: M
authors.initials: M
authors.lastname: Svensson
authors.forename: A
authors.initials: A
authors.lastname: Håkansson
authors.forename: B J
authors.initials: BJ
authors.lastname: Chambers
authors.forename: H G
authors.initials: HG
authors.lastname: Ljunggren
authors.forename: M J
authors.initials: MJ
authors.lastname: Wick
mesh_terms: D000818:Animals; D015496:CD4-Positive T-Lymphocytes / Q000276:immunology*; D018414:CD8-Positive T-Lymphocytes / Q000276:immunology*; D002478:Cells, Cultured; D003713:Dendritic Cells / Q000276:immunology*; D049452:Green Fluorescent Proteins; D007371:Interferon-gamma / Q000096:biosynthesis; D008164:Luminescent Proteins / Q000235:genetics / Q000276:immunology / Q000378:metabolism; D008213:Lymphocyte Activation; D051379:Mice; D008810:Mice, Inbred C57BL; D010047:Ovalbumin / Q000235:genetics / Q000276:immunology / Q000378:metabolism; D010586:Phagocytes / Q000276:immunology; D012481:Salmonella Infections, Animal / Q000276:immunology* / Q000382:microbiology; D012486:Salmonella typhimurium / Q000235:genetics / Q000276:immunology* / Q000378:metabolism; D013154:Spleen / Q000166:cytology / Q000276:immunology
chemical_list: D008164:Luminescent Proteins; D049452:Green Fluorescent Proteins; D007371:Interferon-gamma; D010047:Ovalbumin