title: Fc- and non-Fc-mediated phagocytosis of Borrelia burgdorferi by macrophages.
abstract: The Fc receptor (FcR) for immunoglobulin has been assigned a major role in the ingestion of Borrelia burgdorferi, the Lyme disease spirochete, by macrophages. Yet macrophages readily take up and kill B. burgdorferi that have not been opsonized. By use of doubly-labeled macrophages infected with spirochetes and analyzed by confocal fluorescence microscopy, simultaneous localization of both FcR and spirochetes (opsonized and unopsonized) was quantified. After infection with unopsonized spirochetes, bacterial surface antigen and the FcR remained distinct, confirming the expectation that unopsonized uptake of B. burgdorferi is largely independent of the FcR. A similar lack of colocalization was seen when opsonized spirochetes were ingested by macrophages whose FcRs were sequestered by an immune complex-coated substrate. Furthermore, comparable efficiency of uptake was observed whether or not the FcR was engaged.
authors.affiliation: Department of Internal Medicine, Yale University School of Medicine, New Haven, Connecticut 06520.
authors.forename: R R
authors.initials: RR
authors.lastname: Montgomery
authors.forename: M H
authors.initials: MH
authors.lastname: Nathanson
authors.forename: S E
authors.initials: SE
authors.lastname: Malawista
mesh_terms: D000818:Animals; D015748:Borrelia burgdorferi Group / Q000276:immunology*; D002460:Cell Line; D005455:Fluorescent Antibody Technique; D007700:Kinetics; D008193:Lyme Disease / Q000276:immunology; D008264:Macrophages / Q000276:immunology* / Q000382:microbiology; D051379:Mice; D008856:Microscopy, Fluorescence; D010587:Phagocytosis; D011961:Receptors, Fc / Q000032:analysis / Q000502:physiology*; D013997:Time Factors
chemical_list: D011961:Receptors, Fc