title: Opsonization and phagocytosis of Plasmodium falciparum merozoites measured by flow cytometry.
abstract: A flow cytometric phagocytosis assay was established to investigate the role of anti-merozoite antibody, complement, and cytokines on the phagocytosis of Plasmodium falciparum merozoites by human neutrophils. This assay involved allowing fluorescein isothiocyanate-labeled merozoites to interact with phagocytes and analysis of the cells on a FACScan with Lysis II software. To differentiate the proportion of neutrophil surface-bound merozoites from the merozoites ingested by neutrophils, the fluorescence of bound merozoites was quenched by adding trypan blue. The data showed that sera from malaria-immune individuals in the Solomon Islands and Papua New Guinea promoted merozoite engulfment by neutrophils. The cytokines tumor necrosis factor alpha, gamma interferon, granulocyte-macrophage colony-stimulating factor, and interleukin-1beta significantly increased the amount and the rate of merozoite phagocytosis by neutrophils. Optimum merozoite phagocytosis occurred when both cytokines and anti-malarial antibody were present.
authors.affiliation: Department of Immunopathology, Women's and Children's Hospital, Adelaide, South Australia 5006, Australia. lkumarat@medicine.adelaide.edu.au
authors.forename: L M
authors.initials: LM
authors.lastname: Kumaratilake
authors.forename: A
authors.initials: A
authors.lastname: Ferrante
mesh_terms: D000818:Animals; D000906:Antibodies / Q000276:immunology; D016207:Cytokines / Q000276:immunology; D005434:Flow Cytometry; D016650:Fluorescein-5-isothiocyanate / Q000737:chemistry; D005453:Fluorescence; D006801:Humans; D007371:Interferon-gamma; D008542:Melanesia; D020066:Merozoite Surface Protein 1 / Q000276:immunology*; D009504:Neutrophils / Q000276:immunology; D009895:Opsonin Proteins / Q000502:physiology*; D010219:Papua New Guinea; D010586:Phagocytes / Q000276:immunology; D010587:Phagocytosis / Q000502:physiology*; D010963:Plasmodium falciparum / Q000276:immunology*; D011994:Recombinant Proteins; D012984:Software; D013997:Time Factors; D014343:Trypan Blue / Q000737:chemistry
chemical_list: D000906:Antibodies; D016207:Cytokines; D020066:Merozoite Surface Protein 1; D009895:Opsonin Proteins; D011994:Recombinant Proteins; D007371:Interferon-gamma; D016650:Fluorescein-5-isothiocyanate; D014343:Trypan Blue