Fcgamma receptor-mediated phagocytosis of Plasmodium falciparum-infected erythrocytes in vitro

• Published in: Clinical and experimental immunology 2002-11, Vol.130 (2), p.300-306
• Main Authors: Tebo, A E, Kremsner, P G, Luty, A J F
• Format: Article
• Language: English
• Subjects: Adolescent; Adult; Animals; Antibodies, Protozoan - immunology; Cell Line; Child; Erythrocytes - parasitology; Humans; Immunoglobulin G - blood; Immunoglobulin G - immunology; Malaria, Falciparum - immunology; Middle Aged; Monocytes - immunology; Opsonin Proteins - immunology; Phagocytosis; Plasmodium falciparum; Receptors, IgG - physiology
• ISSN: 0009-9104

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.