title: Fcgamma receptor-mediated phagocytosis of Plasmodium falciparum-infected erythrocytes in vitro.
abstract: Although convincing evidence exists for the role of immunoglobulin G (IgG) antibodies in immunity to malaria, antibody titres do not usually predict protection. In this study we have assessed the interaction between Plasmodium falciparum-infected erythrocytes (PE), opsonized with immune serum containing different amounts of IgG antibody isotypes, with either THP-1 cells, ex-vivo human monocytes or IIAI.6 transfectant cells expressing Fc(gamma)RIIa-Arg/Arg131 or -His/His131 allotypes. Our results show that PMA-treated THP-1 cells were capable of phagocytosing serum-opsonized PE by Fc(gamma)RI (CD64) and Fc(gamma)RIIa (CD32), acting synergistically. The known Fc(gamma)RIIa polymorphism motivated us to examine its influence on IgG isotype-mediated phagocytosis of opsonized PE with human monocytes and the IIAI.6 transfectant cells expressing either allelic forms. Regardless of the cell type, PE phagocytosis with Fc(gamma)RIIa-His/His131 was highest following opsonization with a predominantly IgG3-containing immune serum pool. In contrast, PE phagocytosis with Fc(gamma)RIIa-Arg/Arg131 tended to be higher with an IgG1-containing pool. These results suggest a genetically determined influence of effector cell phenotype on IgG antibody-pathogen interaction in P. falciparum malaria.
authors.affiliation: Department of Parasitology, Institute of Tropical Medicine, University of Tübingen, Germany.
authors.forename: A E
authors.initials: AE
authors.lastname: Tebo
authors.forename: P G
authors.initials: PG
authors.lastname: Kremsner
authors.forename: A J F
authors.initials: AJ
authors.lastname: Luty
mesh_terms: D000293:Adolescent; D000328:Adult; D000818:Animals; D000913:Antibodies, Protozoan / Q000276:immunology*; D002460:Cell Line; D002648:Child; D004912:Erythrocytes / Q000469:parasitology*; D006801:Humans; D007074:Immunoglobulin G / Q000097:blood / Q000276:immunology; D016778:Malaria, Falciparum / Q000276:immunology*; D008875:Middle Aged; D009000:Monocytes / Q000276:immunology*; D009895:Opsonin Proteins / Q000276:immunology; D010587:Phagocytosis; D010963:Plasmodium falciparum; D017452:Receptors, IgG / Q000502:physiology*
chemical_list: D000913:Antibodies, Protozoan; D007074:Immunoglobulin G; D009895:Opsonin Proteins; D017452:Receptors, IgG