title: Nonopsonic phagocytosis of Mycobacterium kansasii by human neutrophils depends on cholesterol and is mediated by CR3 associated with glycosylphosphatidylinositol-anchored proteins.
abstract: Receptors involved in the phagocytosis of microorganisms under nonopsonic conditions have been little studied in neutrophils. Complement receptor type 3 (CR3) is a pattern recognition receptor able to internalize zymosan and C3bi-coated particles. We report that Abs directed against CR3 strongly inhibited nonopsonic phagocytosis of Mycobacterium kansasii in human neutrophils. In these cells CR3 has been found associated with several GPI-anchored proteins localized in cholesterol-rich microdomains (rafts) of the plasma membrane. Cholesterol sequestration by nystatin, filipin, or beta-cyclodextrin as well as treatment of neutrophils with phosphatidylinositol phospholipase C to remove GPI-anchored proteins from the cell surface markedly inhibited phagocytosis of M. kansasii, without affecting phagocytosis of zymosan or serum-opsonized M. kansasii. Abs directed against several GPI-anchored proteins inhibited phagocytosis of M. kansasii, but not of zymosan. N:-acetyl-D-glucosamine, which is known to disrupt interactions between CR3 and GPI proteins, also strongly diminished phagocytosis of these mycobacteria. In conclusion, phagocytosis of M. kansasii involved CR3, GPI-anchored receptors, and cholesterol. In contrast, phagocytosis of zymosan or opsonized particles involved CR3, but not cholesterol or GPI proteins. We propose that CR3, when associated with a GPI protein, relocates in cholesterol-rich domains where M. kansasii are internalized. When CR3 is not associated with a GPI protein, it remains outside of these domains and mediates phagocytosis of zymosan and opsonized particles, but not of M. kansasii.
authors.affiliation: Centre National de la Recherche Scientifique, Unité Mixte de Recherche 5089, Institut de Pharmacologie et de Biologie Structurale, Toulouse, France.
authors.forename: P
authors.initials: P
authors.lastname: Peyron
authors.forename: C
authors.initials: C
authors.lastname: Bordier
authors.forename: E N
authors.initials: EN
authors.lastname: N'Diaye
authors.forename: I
authors.initials: I
authors.lastname: Maridonneau-Parini
mesh_terms: D000117:Acetylglucosamine / Q000494:pharmacology; D000951:Antigens, Neoplasm; D018958:CD55 Antigens / Q000276:immunology / Q000378:metabolism; D015815:Cell Adhesion Molecules; D002784:Cholesterol / Q000502:physiology*; D017261:Glycosylphosphatidylinositols / Q000276:immunology / Q000378:metabolism*; D006801:Humans; D018950:Lipopolysaccharide Receptors / Q000276:immunology / Q000378:metabolism; D016177:Macrophage-1 Antigen / Q000502:physiology*; D008562:Membrane Glycoproteins / Q000276:immunology / Q000378:metabolism; D021962:Membrane Microdomains / Q000276:immunology; D019909:Mycobacterium kansasii / Q000187:drug effects / Q000276:immunology*; D009504:Neutrophils / Q000187:drug effects / Q000276:immunology* / Q000378:metabolism / Q000382:microbiology*; D009895:Opsonin Proteins / Q000276:immunology*; D010587:Phagocytosis / Q000187:drug effects / Q000276:immunology*; D017452:Receptors, IgG / Q000276:immunology / Q000378:metabolism
chemical_list: D000951:Antigens, Neoplasm; D018958:CD55 Antigens; D015815:Cell Adhesion Molecules; D017261:Glycosylphosphatidylinositols; D018950:Lipopolysaccharide Receptors; D016177:Macrophage-1 Antigen; D008562:Membrane Glycoproteins; D009895:Opsonin Proteins; D017452:Receptors, IgG; D002784:Cholesterol; D000117:Acetylglucosamine