title: Altered surface distribution of both C3b receptors and Fc receptors on neutrophils induced by anti-C3b receptor or aggregated IgG.
abstract: Human neutrophils to which monospecific Fab' or F(ab')2 anti-C3b receptor had been bound at 0 degrees C were incubated for timed intervals at temperatures ranging from 0 degrees C to 37 degrees C, after which the cells were labeled with TRITC -conjugated second antibody. Neutrophils bearing Fab' anti-C3b receptor and incubated for up to 30 min at 37 degrees C, and cells bearing F(ab')2 anti-C3b receptor and incubated at 0 degrees C, exhibited diffusely distributed punctate clusters of receptors. Neutrophils bearing the bivalent anti-receptor and incubated at 30 degrees C or 37 degrees C for 5 min had redistributed C3b receptors into caps and patches that were associated with subplasmalemmal accumulations of myosin. The redistribution of cross-linked C3b receptors was inhibited by pretreatment of the neutrophils with either cytochalasin D or chlorpromazine. On approximately one-half of the cells demonstrating capped C3b receptors there was a corresponding redistribution of Fc receptors, as demonstrated by subsequent binding of FITC-aggregated IgG (FITC agg-IgG). In contrast, capping of C3b receptors did not alter the diffuse distribution of HLA-A on these cells. Cross-linking of Fc receptors on neutrophils by FITC agg-IgG also induced temperature-dependent capping of these receptors that was inhibited by cytochalasin D and chlorpromazine. In approximately one-half of the cells demonstrating capped Fc receptors, subsequent labeling of C3b receptors revealed a similar redistribution of these receptors. Thus, the neutrophil responds to cross-linking of either C3b receptors or Fc receptors by a cytoskeletal-dependent rearrangement of both receptors that causes their overlapping topographic distribution, demonstrating a form of cooperative interaction between these two types of receptors that are involved in the phagocytic reactions of these cells.
mesh_terms: D000818:Animals; D000911:Antibodies, Monoclonal / Q000502:physiology*; D002462:Cell Membrane / Q000378:metabolism; D003432:Cross-Linking Reagents / Q000494:pharmacology; D005455:Fluorescent Antibody Technique; D006801:Humans; D007140:Immunoglobulin Fab Fragments; D007074:Immunoglobulin G / Q000502:physiology*; D007152:Immunologic Capping; D009504:Neutrophils / Q000378:metabolism*; D011817:Rabbits; D011951:Receptors, Complement / Q000032:analysis* / Q000276:immunology; D017463:Receptors, Complement 3b; D011961:Receptors, Fc / Q000032:analysis*
chemical_list: D000911:Antibodies, Monoclonal; D003432:Cross-Linking Reagents; D007140:Immunoglobulin Fab Fragments; D007074:Immunoglobulin G; D011951:Receptors, Complement; D017463:Receptors, Complement 3b; D011961:Receptors, Fc