title: Study of Fc gamma murine macrophage receptors (Fc gamma R) in the internalization of Histoplasma capsulatum yeasts.
abstract: Reports about Fc gamma R involvement in the phagocytosis of Histoplasma capsulatum yeast are contradictory. Fungal cells were incubated with anti-Histoplasma murine IgG or normal IgG as control. The opsonized yeasts were adjusted and spread on a J774.2 macrophage cell line monolayer. Yeast cells were allowed to attach to the monolayers at 4 degrees C for 1 h prior to initiating the internalization step of the phagocytic process, by shifting the cells to 37 degrees C. The participation of Fc gamma R in the internalization of yeast was monitored by radioiodination labelling of the macrophage surface proteins, and rosette-forming cells for erythrocytes coated with antibodies (RFC-EA). Results showed decreased [125I]-incorporation on the macrophage surface proteins at 15 min post-anti-Histoplasma IgG opsonized yeast infection. The same was observed when high and low virulent H. capsulatum strains were used. A decrease of RFC percentage was also observed at 15 min after IgG opsonized yeast phagocytosis. Results support the disappearance of Fc gamma R at 15 min from the surface of the macrophage that had ingested anti-Histoplasma IgG opsonized yeasts. The recovery of [125I]-counts and the RFC response at a longer time of phagocytosis suggest a possible Fc gamma R recycling mechanism.
authors.affiliation: Departamento de Microbiología y Parasitología, Facultad de Medicina, UNAM, México, D.F.
authors.forename: M L
authors.initials: ML
authors.lastname: Taylor
authors.forename: B
authors.initials: B
authors.lastname: Rico
authors.forename: F
authors.initials: F
authors.lastname: Goodsaid
mesh_terms: D000818:Animals; D000908:Antibodies, Fungal / Q000276:immunology; D006658:Histoplasma / Q000276:immunology / Q000472:pathogenicity; D007114:Immunization; D007074:Immunoglobulin G / Q000276:immunology; D008264:Macrophages / Q000502:physiology*; D008297:Male; D051379:Mice; D008807:Mice, Inbred BALB C; D009895:Opsonin Proteins / Q000276:immunology; D010587:Phagocytosis; D017452:Receptors, IgG / Q000502:physiology*; D012397:Rosette Formation; D014407:Tumor Cells, Cultured; D014774:Virulence
chemical_list: D000908:Antibodies, Fungal; D007074:Immunoglobulin G; D009895:Opsonin Proteins; D017452:Receptors, IgG