title: Factors affecting the redistribution of surface-bound concanavalin A on human polymorphonuclear leukocytes.
abstract: Human neutrophil polymorphonuclear leukocytes (PMN) were studied to determine the influence of cellular locomotion upon the redistribution and capping of concanavalin A (Con A). Con A was detected by fluorescence (using Con A conjugated to fluorescein isothiocyanate [Con A-FITC]), or on shadow-cast replicas (using Busycon canaliculatum hemocyanin as a marker for Con A). After labeling with Con A 100 microg/ml at 4 degrees C and warming to 37 degrees C, locomotion occurred, and the Con A quickly aggregated into a cap at the trailing end of the cell. When locomotion was inhibited (with cytochalasin B, or by incubation in serum-free medium at 18 degrees C) Con A rapidly formed a cap over the central region of the cell. Iodoacetamide inhibited capping. PMN labeled with FITC, a monovalent ligand, developed caps at the tail only on motile cells; FITC remained dispersed on immobilized cells. PMN exposed to Con A 100 microg/ml at 37 degrees C bound more lectin than at 4 degrees C, became immobilized, and showed slow central capping. The Con A soon became internalized to form a perinuclear ring. Such treatment in the presence of cytochalasin B resulted in the quick formation of persistent central caps. Colchicine (or prior cooling) protected PMN from the immobilizing effect of Con A, and tail caps were found on 30-40% of cells. Immobilization of colchicine-treated cells caused Con A to remain in dispersed clusters. Thus, capping on PMN is a temperature- and energy-dependent process that proceeds independently of cellular locomotion, provided a colchicine-sensitive system is intact and the ligand is capable of cross linking receptors. On the other hand, if the cell does move, it appears that ligands may be swept into a cap at the tail whether cross-linking occurs or not.
mesh_terms: D001666:Binding Sites, Antibody; D002462:Cell Membrane / Q000276:immunology; D002465:Cell Movement; D003078:Colchicine / Q000494:pharmacology; D003208:Concanavalin A; D003571:Cytochalasin B / Q000494:pharmacology; D003593:Cytoplasm; D006433:Hemocyanins / Q000276:immunology; D006801:Humans; D007461:Iodoacetates / Q000494:pharmacology; D008024:Ligands; D008856:Microscopy, Fluorescence; D009504:Neutrophils / Q000276:immunology* / Q000648:ultrastructure; D013499:Surface Properties; D013696:Temperature
chemical_list: D007461:Iodoacetates; D008024:Ligands; D003208:Concanavalin A; D003571:Cytochalasin B; D006433:Hemocyanins; D003078:Colchicine