title: Primed antigen-specific CD4+ T cells are required for NK cell activation in vivo upon Leishmania major infection.
abstract: The ability of NK cells to rapidly produce IFN-gamma is an important innate mechanism of resistance to many pathogens including Leishmania major. Molecular and cellular components involved in NK cell activation in vivo are still poorly defined, although a central role for dendritic cells has been described. In this study, we demonstrate that Ag-specific CD4(+) T cells are required to initiate NK cell activation early on in draining lymph nodes of L. major-infected mice. We show that early IFN-gamma secretion by NK cells is controlled by IL-2 and IL-12 and is dependent on CD40/CD40L interaction. These findings suggest that newly primed Ag-specific CD4(+) T cells could directly activate NK cells through the secretion of IL-2 but also indirectly through the regulation of IL-12 secretion by dendritic cells. Our results reveal an unappreciated role for Ag-specific CD4(+) T cells in the initiation of NK cell activation in vivo upon L. major infection and demonstrate bidirectional regulations between innate and adaptive immunity.
authors.affiliation: Centre National de la Recherche Scientifique/Université de Nice-Sophia Antipolis, Unité Mixte de Recherche 6097, Valbonne, France.
authors.forename: Franck
authors.initials: F
authors.lastname: Bihl
authors.forename: Julien
authors.initials: J
authors.lastname: Pecheur
authors.forename: Béatrice
authors.initials: B
authors.lastname: Bréart
authors.forename: Gwenola
authors.initials: G
authors.lastname: Poupon
authors.forename: Julie
authors.initials: J
authors.lastname: Cazareth
authors.forename: Valérie
authors.initials: V
authors.lastname: Julia
authors.forename: Nicolas
authors.initials: N
authors.lastname: Glaichenhaus
authors.forename: Véronique M
authors.initials: VM
authors.lastname: Braud
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D000941:Antigens / Q000276:immunology*; D015496:CD4-Positive T-Lymphocytes / Q000276:immunology* / Q000378:metabolism; D002478:Cells, Cultured; D003713:Dendritic Cells / Q000276:immunology / Q000378:metabolism; D005260:Female; D005434:Flow Cytometry; D007371:Interferon-gamma / Q000276:immunology / Q000378:metabolism; D018664:Interleukin-12 / Q000276:immunology / Q000378:metabolism; D007376:Interleukin-2 / Q000235:genetics / Q000276:immunology / Q000378:metabolism; D007694:Killer Cells, Natural / Q000276:immunology* / Q000378:metabolism; D018320:Leishmania major / Q000276:immunology; D016773:Leishmaniasis, Cutaneous / Q000276:immunology* / Q000469:parasitology; D008213:Lymphocyte Activation / Q000276:immunology; D008297:Male; D051379:Mice; D008807:Mice, Inbred BALB C; D008810:Mice, Inbred C57BL; D018345:Mice, Knockout; D016513:Mice, SCID; D008969:Molecular Sequence Data; D013997:Time Factors
chemical_list: D000941:Antigens; D007376:Interleukin-2; D018664:Interleukin-12; D007371:Interferon-gamma