title: Urokinase receptor (uPAR) regulates complement receptor 3 (CR3)-mediated neutrophil phagocytosis.
abstract: Urokinase receptor (uPAR) associates in cis with complement receptor 3 (CR3). In the present study, we addressed whether this coupling regulates CR3-mediated phagocytosis. CR3-mediated attachment of iC3b-opsonized sheep red blood cells to human neutrophils and internalization of these cells were reduced by removal of cell-bound uPAR by phosphatidylinositol-specific phospholipase C and reconstituted in the presence of soluble uPAR. The attachment and internalization were suppressed in the presence of anti-uPAR polyclonal antibody, proteolytically inactive urokinase and saccharides that disrupt interaction of uPAR with CR3. Thus, uPAR acts as a cofactor for iC3b binding to CR3 and regulates CR3-mediated phagocytosis.
authors.affiliation: Department of Biological and Medical Chemistry, Faculty of Fundamental Medicine, Moscow State University, Lomonosovsky pr, 31-5, Moscow 119192, Russia. bpliyev@cardio.ru
authors.forename: Boris K
authors.initials: BK
authors.lastname: Pliyev
authors.forename: Tatiana I
authors.initials: TI
authors.lastname: Arefieva
authors.forename: Mikhail Yu
authors.initials: MY
authors.lastname: Menshikov
mesh_terms: D002462:Cell Membrane / Q000378:metabolism; D003179:Complement C3b / Q000378:metabolism*; D006801:Humans; D016177:Macrophage-1 Antigen / Q000378:metabolism*; D009504:Neutrophils / Q000276:immunology*; D010587:Phagocytosis; D055293:Receptors, Urokinase Plasminogen Activator / Q000378:metabolism*
chemical_list: D016177:Macrophage-1 Antigen; D055293:Receptors, Urokinase Plasminogen Activator; D003179:Complement C3b