title: Role of T cells in innate and adaptive immunity against murine Burkholderia pseudomallei infection.
abstract: Antigen-specific T cells are important sources of interferon (IFN)-gamma for acquired immunity to intracellular pathogens, but they can also produce IFN- gamma directly via a "bystander" activation pathway in response to proinflammatory cytokines. We investigated the in vivo role of cytokine- versus antigen-mediated T cell activation in resistance to the pathogenic bacterium Burkholderia pseudomallei. IFN-gamma, interleukin (IL)-12, and IL-18 were essential for initial bacterial control in infected mice. B. pseudomallei infection rapidly generated a potent IFN-gamma response from natural killer (NK) cells, NK T cells, conventional T cells, and other cell types within 16 h after infection, in an IL-12- and IL-18-dependent manner. However, early T cell- and NK cell-derived IFN-gamma responses were functionally redundant in cell depletion studies, with IFN-gamma produced by other cell types, such as major histocompatibility complex class II(int) F4/80(+) macrophages being sufficient for initial resistance. In contrast, B. pseudomallei-specific CD4(+) T cells played an important role during the later stage of infection. Thus, the T cell response to primary B. pseudomallei infection is biphasic, an early cytokine-induced phase in which T cells appear to be functionally redundant for initial bacterial clearance, followed by a later antigen-induced phase in which B. pseudomallei-specific T cells, in particular CD4(+) T cells, are important for host resistance.
authors.affiliation: Immunology Unit, Department of Infectious and Tropical Diseases, London School of Hygiene and Tropical Medicine, UK.
authors.forename: Ashraful
authors.initials: A
authors.lastname: Haque
authors.forename: Anna
authors.initials: A
authors.lastname: Easton
authors.forename: Debbie
authors.initials: D
authors.lastname: Smith
authors.forename: Anne
authors.initials: A
authors.lastname: O'Garra
authors.forename: Nico
authors.initials: N
authors.lastname: Van Rooijen
authors.forename: Ganjana
authors.initials: G
authors.lastname: Lertmemongkolchai
authors.forename: Richard W
authors.initials: RW
authors.lastname: Titball
authors.forename: Gregory J
authors.initials: GJ
authors.lastname: Bancroft
mesh_terms: D000818:Animals; D016957:Burkholderia pseudomallei / Q000276:immunology*; D016207:Cytokines / Q000378:metabolism; D005260:Female; D006801:Humans; D007371:Interferon-gamma / Q000096:biosynthesis*; D007694:Killer Cells, Natural / Q000276:immunology / Q000378:metabolism; D008554:Melioidosis / Q000276:immunology* / Q000382:microbiology; D051379:Mice; D008810:Mice, Inbred C57BL; D013047:Specific Pathogen-Free Organisms; D013601:T-Lymphocytes / Q000276:immunology* / Q000378:metabolism
chemical_list: D016207:Cytokines; D007371:Interferon-gamma