title: Efficient measurement of opsonising antibodies to Plasmodium falciparum merozoites.
abstract: BACKGROUND
  Antibodies targeting merozoites are important in protection from malaria. Therefore, merozoite surface proteins are attractive vaccine candidates. There is a need for robust functional assays to investigate mechanisms of acquired immunity and vaccine efficacy. To date, the study of merozoite phagocytosis has been confounded by the complexity and variability of in vitro assays.
  
  
  RESULTS
  We have developed a new flow cytometry-based merozoite phagocytosis assay. An optimized merozoite preparation technique produced high yields of merozoites separated from haemozoin. Phagocytosis by the undifferentiated THP-1 monocytic cell line was mediated only by Fc Receptors, and was therefore ideal for studying opsonising antibody responses. The assay showed robust phagocytosis with highly diluted immune sera and strong inter-assay correlation. The assay effectively measured differences in opsonisation-dependent phagocytosis among individuals.
  
  
  CONCLUSIONS
  This highly reproducible assay has potential applications in assessing the role of opsonic phagocytosis in naturally acquired immunity and vaccine trials.
authors.affiliation: Walter and Eliza Hall Institute for Medical Research, Parkville, Victoria, Australia.
authors.forename: Danika L
authors.initials: DL
authors.lastname: Hill
authors.forename: Emily M
authors.initials: EM
authors.lastname: Eriksson
authors.forename: Amandine B
authors.initials: AB
authors.lastname: Carmagnac
authors.forename: Danny W
authors.initials: DW
authors.lastname: Wilson
authors.forename: Alan F
authors.initials: AF
authors.lastname: Cowman
authors.forename: Diana S
authors.initials: DS
authors.lastname: Hansen
authors.forename: Louis
authors.initials: L
authors.lastname: Schofield
mesh_terms: D000293:Adolescent; D000328:Adult; D000913:Antibodies, Protozoan / Q000097:blood* / Q000276:immunology; D000953:Antigens, Protozoan / Q000276:immunology; D002478:Cells, Cultured; D002648:Child; D002675:Child, Preschool; D005434:Flow Cytometry / Q000379:methods*; D019084:Fluorescent Antibody Technique, Indirect; D006801:Humans; D015151:Immunoblotting; D016778:Malaria, Falciparum / Q000097:blood / Q000276:immunology* / Q000517:prevention & control; D052940:Merozoites / Q000276:immunology*; D008875:Middle Aged; D009000:Monocytes / Q000276:immunology* / Q000469:parasitology; D009895:Opsonin Proteins / Q000276:immunology*; D010587:Phagocytosis / Q000502:physiology; D010963:Plasmodium falciparum / Q000276:immunology*; D011961:Receptors, Fc / Q000276:immunology; D015203:Reproducibility of Results; D055815:Young Adult
chemical_list: D000913:Antibodies, Protozoan; D000953:Antigens, Protozoan; D009895:Opsonin Proteins; D011961:Receptors, Fc