title: Migrating monocytes recruited to the spleen play an important role in control of blood stage malaria.
abstract: Host responses controlling blood-stage malaria include both innate and acquired immune effector mechanisms. During Plasmodium chabaudi infection in mice, a population of CD11b(high)Ly6C(+) monocytes are generated in bone marrow, most of which depend on the chemokine receptor CCR2 for migration from bone marrow to the spleen. In the absence of this receptor mice harbor higher parasitemias. Most importantly, splenic CD11b(high)Ly6C(+) cells from P chabaudi-infected wild-type mice significantly reduce acute-stage parasitemia in CCR2(-/-) mice. The CD11b(high)Ly6C(+) cells in this malaria infection display effector functions such as production of inducible nitric oxide synthase and reactive oxygen intermediates, and phagocytose P chabaudi parasites in vitro, and in a proportion of the cells, in vivo in the spleen, suggesting possible mechanisms of parasite killing. In contrast to monocyte-derived dendritic cells, CD11b(high)Ly6C(+) cells isolated from malaria-infected mice express low levels of major histocompatibility complex II and have limited ability to present the P chabaudi antigen, merozoite surface protein-1, to specific T-cell receptor transgenic CD4 T cells and fail to activate these T cells. We propose that these monocytes, which are rapidly produced in the bone marrow as part of the early defense mechanism against invading pathogens, are important for controlling blood-stage malaria parasites.
authors.affiliation: Division of Parasitology, Medical Research Council (MRC) National Institute for Medical Research, London, UK.
authors.forename: Anne-Marit
authors.initials: AM
authors.lastname: Sponaas
authors.forename: Ana Paula
authors.initials: AP
authors.lastname: Freitas do Rosario
authors.forename: Cecile
authors.initials: C
authors.lastname: Voisine
authors.forename: Beatris
authors.initials: B
authors.lastname: Mastelic
authors.forename: Joanne
authors.initials: J
authors.lastname: Thompson
authors.forename: Sandra
authors.initials: S
authors.lastname: Koernig
authors.forename: William
authors.initials: W
authors.lastname: Jarra
authors.forename: Laurent
authors.initials: L
authors.lastname: Renia
authors.forename: Marjorie
authors.initials: M
authors.lastname: Mauduit
authors.forename: Alexandre J
authors.initials: AJ
authors.lastname: Potocnik
authors.forename: Jean
authors.initials: J
authors.lastname: Langhorne
mesh_terms: D000818:Animals; D000938:Antigen-Presenting Cells / Q000378:metabolism / Q000469:parasitology / Q000473:pathology; D000950:Antigens, Ly / Q000378:metabolism; D039481:CD11b Antigen / Q000378:metabolism; D015496:CD4-Positive T-Lymphocytes / Q000378:metabolism / Q000469:parasitology / Q000473:pathology; D002465:Cell Movement / Q000502:physiology*; D005434:Flow Cytometry; D006790:Host-Parasite Interactions; D008288:Malaria / Q000097:blood / Q000469:parasitology; D051379:Mice; D008807:Mice, Inbred BALB C; D008810:Mice, Inbred C57BL; D018345:Mice, Knockout; D009000:Monocytes / Q000378:metabolism / Q000469:parasitology* / Q000473:pathology; D052247:Nitric Oxide Synthase Type II / Q000378:metabolism; D018512:Parasitemia / Q000378:metabolism; D010587:Phagocytosis / Q000502:physiology; D016788:Plasmodium chabaudi / Q000502:physiology*; D054390:Receptors, CCR2 / Q000235:genetics / Q000378:metabolism; D013154:Spleen / Q000378:metabolism / Q000469:parasitology* / Q000473:pathology; D013601:T-Lymphocytes / Q000378:metabolism / Q000469:parasitology / Q000473:pathology; D014409:Tumor Necrosis Factor-alpha / Q000378:metabolism
chemical_list: D000950:Antigens, Ly; D039481:CD11b Antigen; C515335:Ccr2 protein, mouse; C494192:Ly-6C antigen, mouse; D054390:Receptors, CCR2; D014409:Tumor Necrosis Factor-alpha; D052247:Nitric Oxide Synthase Type II