title: A Robust Phagocytosis Assay to Evaluate the Opsonic Activity of Antibodies against Plasmodium falciparum-Infected Erythrocytes.
abstract: Infection with Plasmodium falciparum parasites causes the majority of malaria-related morbidity and mortality. Constant exposure to the pathogen leads to the acquisition of antibodies and high levels of antibodies have been associated with clinical protection against malaria. A possible protective mechanism is the opsonization of parasites, or malaria-infected erythrocytes (IEs), for phagocytic clearance. Current assays use adherent or chemically differentiated THP-1 cells to evaluate opsonic antibodies in patients' samples, but these assays are often time consuming and damage the effector cells. We have developed a high throughput flow cytometry-based phagocytosis assay using undifferentiated THP-1 cells to quantify the opsonic activity against late stage P. falciparum-IEs. Opsonic antibodies bound to IEs promote their phagocytic uptake through Fcγ receptors found on THP-1 cells. Moreover, undifferentiated THP-1 cells do not express CD36, a surface scavenger receptor that promotes non-opsonic phagocytosis. This technical advance allows quantification of opsonic antibodies and is an important tool for the performance of large, population-based studies of malaria immunity, and to provide a significant increase in the statistical power for such studies.
authors.affiliation: Department of Medicine, The University of Melbourne, The Doherty Institute Level 5, Parkville, VIC, 3010, Australia. andrew.teo@uqconnect.edu.au.
authors.forename: Andrew
authors.initials: A
authors.lastname: Teo
authors.affiliation: Department of Medicine, The University of Melbourne, The Doherty Institute Level 5, Parkville, VIC, 3010, Australia.|Victorian Infectious Diseases Service, The Doherty Institute, Parkville, VIC, Australia.
authors.forename: Wina
authors.initials: W
authors.lastname: Hasang
authors.affiliation: Centre for Biomedical Research, Macfarlane Burnet Institute of Medical Research, Melbourne, VIC, 3004, Australia.
authors.forename: Philippe
authors.initials: P
authors.lastname: Boeuf
authors.affiliation: Department of Medicine, The University of Melbourne, The Doherty Institute Level 5, Parkville, VIC, 3010, Australia.|Victorian Infectious Diseases Service, The Doherty Institute, Parkville, VIC, Australia.
authors.forename: Stephen
authors.initials: S
authors.lastname: Rogerson
mesh_terms: D000913:Antibodies, Protozoan / Q000097:blood / Q000276:immunology*; D000953:Antigens, Protozoan / Q000097:blood / Q000276:immunology; D004912:Erythrocytes / Q000276:immunology / Q000469:parasitology; D005434:Flow Cytometry / Q000379:methods*; D006801:Humans; D007074:Immunoglobulin G / Q000097:blood; D016778:Malaria, Falciparum / Q000276:immunology* / Q000469:parasitology; D009000:Monocytes / Q000276:immunology; D010587:Phagocytosis / Q000276:immunology; D010963:Plasmodium falciparum / Q000276:immunology* / Q000472:pathogenicity
chemical_list: D000913:Antibodies, Protozoan; D000953:Antigens, Protozoan; D007074:Immunoglobulin G
keywords: High throughput; Malaria; Opsonizing; Phagocytosis; Population-based studies