title: CD11c- and CD11b-expressing mouse leukocytes transport single Toxoplasma gondii tachyzoites to the brain.
abstract: The protozoan parasite Toxoplasma gondii enters hosts through the intestinal mucosa and colonizes distant tissues such as the brain, where its progeny persists for a lifetime. We investigated the role of CD11c- and CD11b-expressing leukocytes in T. gondii transport during the early step of parasitism from the mouse small intestine and during subsequent parasite localization in the brain. Following intragastric inoculation of cyst-containing parasites in mice, CD11c+ dendritic cells from the intestinal lamina propria, the Peyer patches, and the mesenteric lymph nodes were parasitized while in the blood, parasites were associated with the CD11c- CD11b+ monocytes. Using adoptive transfer experiments, we demonstrated that these parasitized cells triggered a parasitic process in the brain of naive recipient mice. Ex vivo analysis of parasitized leukocytes showed that single tachyzoites remained at the cell periphery, often surrounded by the host cell plasma membrane, but did not divide. Using either a dye that labels circulating leukocytes or an antibody known to prevent CD11b+ circulating leukocytes from leaving the microvascular bed lumen, and chimeric mice in which the hematopoietic cells expressed the green fluorescent protein, we established that T. gondii zoites hijacked CD11b+ leukocytes to reach the brain extravascular space.
authors.affiliation: Département des Maladies Infectieuses, Institut Cochin, Institut National de la Santé et de la Recherche Médicale U567-Centre National de la Recherche Scientifique Unité Mixte de Recherche 8104, 22 rue Méchain, 75014 Paris, France.
authors.forename: Nathalie
authors.initials: N
authors.lastname: Courret
authors.forename: Sylvie
authors.initials: S
authors.lastname: Darche
authors.forename: Pierre
authors.initials: P
authors.lastname: Sonigo
authors.forename: Geneviève
authors.initials: G
authors.lastname: Milon
authors.forename: Dominique
authors.initials: D
authors.lastname: Buzoni-Gâtel
authors.forename: Isabelle
authors.initials: I
authors.lastname: Tardieux
mesh_terms: D000818:Animals; D001921:Brain / Q000469:parasitology*; D039481:CD11b Antigen; D039521:CD11c Antigen; D003713:Dendritic Cells / Q000469:parasitology; D049452:Green Fluorescent Proteins / Q000032:analysis / Q000235:genetics; D016130:Immunophenotyping; D007421:Intestine, Small / Q000469:parasitology; D007962:Leukocytes / Q000276:immunology / Q000469:parasitology*; D008198:Lymph Nodes / Q000473:pathology; D051379:Mice; D008815:Mice, Inbred Strains; D008822:Mice, Transgenic; D014122:Toxoplasma / Q000502:physiology*; D014123:Toxoplasmosis / Q000469:parasitology
chemical_list: D039481:CD11b Antigen; D039521:CD11c Antigen; D049452:Green Fluorescent Proteins