Visualization of the transfer reaction: tracking immune complexes from erythrocyte complement receptor 1 to macrophages.
Immune complexes (IC) bound to human erythrocytes (E) via complement receptor 1 (CR1) are transferred to phagocytes in the liver and spleen. In an in vitro model system using bispecific mAb reagents (antigen-based heteropolymers) to link IC to E, we have made time-lapse movies in which fluorescently labeled IC cross the E-human macrophage interface and remain associated with the macrophage. Both these movies and fixed-time experiments reveal transfer intermediates in which IC hinge E to macrophages. Examination of model macrophages after transfer indicates that the majority of IC are on the surface at short times (2 min) but are internalized at long times (1-4 h). More than half of the surface IC colocalize with CR1 at 2 min. This evidence supports a model in which CR1-bound IC provide a secure linkage between E and macrophages, allowing rearrangements of the macrophage surface necessary for release of CR1, and IC, from the E.
Craig
Maria L
ML
Department of Biochemistry and Molecular Genetics, University of Virginia School of Medicine, Charlottesville, Virginia 22908, USA.
Bankovich
Alexander J
AJ
Taylor
Ronald P
RP
D018033:Antibodies, Bispecific / Q000276:immunology; D000936:Antigen-Antibody Complex / Q000276:immunology* / Q000378:metabolism; D004247:DNA / Q000276:immunology; D004910:Erythrocyte Membrane / Q000276:immunology* / Q000378:metabolism; D005434:Flow Cytometry; D006801:Humans; D007104:Immune Adherence Reaction; D007074:Immunoglobulin G / Q000235:genetics / Q000276:immunology; D008180:Lupus Erythematosus, Systemic / Q000276:immunology*; D008264:Macrophages / Q000276:immunology* / Q000378:metabolism; D008856:Microscopy, Fluorescence; D011951:Receptors, Complement / Q000276:immunology* / Q000378:metabolism; D017463:Receptors, Complement 3b / Q000276:immunology*; D011961:Receptors, Fc / Q000276:immunology; D020298:U937 Cells
D018033:Antibodies, Bispecific; D000936:Antigen-Antibody Complex; D007074:Immunoglobulin G; D011951:Receptors, Complement; D017463:Receptors, Complement 3b; D011961:Receptors, Fc; D004247:DNA