title: Granulophysin is located in the membrane of azurophilic granules in human neutrophils and mobilizes to the plasma membrane following cell stimulation.
abstract: Granulophysin, a protein described in platelet dense granule membranes, has been shown to be similar or identical to CD63, a lysosomal membrane protein. We have previously shown granulophysin to be present in neutrophils using immunofluorescence. We now localize granulophysin to the neutrophil azurophilic granules by fine structural immunocytochemistry. Granulophysin expression on the surface membrane of the neutrophil is increased following stimulation of the cells, demonstrated by flow cytometry and fine structural immunocytochemistry. A similar pattern is shown for an anti-CD63 antibody. Incubation of activated neutrophils with D545, a monoclonal antibody to granulophysin, blocks subsequent binding of anti-CD63 antibodies to the cell surface, and anti-CD63 antibodies prevent subsequent binding of D545 as assessed by flow cytometry and immunoblotting. Our results support the homology of CD63 and granulophysin previously demonstrated in platelets and confirm CD63 as an activation marker in neutrophils and the first azurophilic granule membrane marker of neutrophils.
authors.affiliation: Department of Pediatrics, University of Manitoba, Winnipeg, Canada.
authors.forename: B P
authors.initials: BP
authors.lastname: Cham
authors.forename: J M
authors.initials: JM
authors.lastname: Gerrard
authors.forename: D F
authors.initials: DF
authors.lastname: Bainton
mesh_terms: D015703:Antigens, CD / Q000032:analysis* / Q000378:metabolism*; D001399:Azure Stains; D001692:Biological Transport / Q000502:physiology; D015153:Blotting, Western; D002462:Cell Membrane / Q000737:chemistry / Q000378:metabolism / Q000648:ultrastructure; D003594:Cytoplasmic Granules / Q000737:chemistry*; D005434:Flow Cytometry; D005455:Fluorescent Antibody Technique; D006801:Humans; D007150:Immunohistochemistry; D016253:Microscopy, Immunoelectron; D009504:Neutrophils / Q000737:chemistry* / Q000378:metabolism / Q000648:ultrastructure*; D010980:Platelet Membrane Glycoproteins / Q000032:analysis* / Q000378:metabolism*; D060149:Tetraspanin 30
chemical_list: D015703:Antigens, CD; D001399:Azure Stains; C554586:CD63 protein, human; D010980:Platelet Membrane Glycoproteins; D060149:Tetraspanin 30