The Neutrophil-specific Antigen CD177 Is a Counter-receptor for Platelet Endothelial Cell Adhesion Molecule-1 (CD31)

Abstract

Human neutrophil-specific CD177 (NB1 and PRV-1) has been reported to be up-regulated in a number of inflammatory settings, including bacterial infection and granulocyte-colonystimulating factor application. Little is known about its function. By flow cytometry and immunoprecipitation studies, we identified platelet endothelial cell adhesion molecule-1 (PECAM-1) as a binding partner of CD177. Real-time proteinprotein analysis using surface plasmon resonance confirmed a cation-dependent, specific interaction between CD177 and the heterophilic domains of PECAM-1. Monoclonal antibodies against CD177 and against PECAM-1 domain 6 inhibited adhesion of U937 cells stably expressing CD177 to immobilized PECAM-1. Transendothelial migration of human neutrophils was also inhibited by these antibodies. Our findings provide direct evidence that neutrophil-specific CD177 is a heterophilic binding partner of PECAM-1. This interaction may constitute a new pathway that participates in neutrophil transmigration.CD177 (NB1 and PRV-1) is a 58-to 64-kDa glycosylphosphatidylinositol-anchored glycoprotein expressed exclusively by neutrophils, neutrophilic metamyelocytes, and myelocytes, but not by any other blood cells (1, 2). We and others elucidated its primary structure by sequencing the NB1 and PRV-1 genes, which later turned out to be two alleles of a single CD177 gene (3-5). The surface expression of CD177 is unique in that only a subpopulation of neutrophils expresses this protein on the cell surface, with the mean size of the CD177-positive subpopulation ranging from 45% to 65% (2, 6).CD177 has been well studied as a target antigen in immunemediated disorders. During pregnancy, women with a CD177 null phenotype are prone to produce alloantibodies against CD177 that cross the placenta, react with fetal neutrophils, and cause neutropenia of the newborn. This mechanism let to the initial discovery of the NB1 antigen in 1971 (7). Alloantibodies to CD177, present in blood products obtained from immunized donors, have also been implicated as mediators of transfusionrelated acute lung injury (8).Although well characterized as an immunotarget, the function of CD177 is largely unknown. It has been reported that CD177 is up-regulated on the neutrophil surface upon stimulation, including during severe bacterial infections, and following granulocyte-colony-stimulating factor treatment (9). In addition, antibody-mediated clustering of CD177 primes the N-formyl-methionyl-leucyl-phenylalanine (fMLP) 3 -activated respiratory burst reaction of the neutrophil (8). Taken together, these observations make it reasonable to suppose that CD177 may be involved in processes of neutrophil-mediated host defense. One preliminary study suggests a participation of CD177 in neutrophil-endothelial cell interaction (10). The latter observation is in line with the fact that CD177, as a member of the leukocyte antigen-6 superfamily, shares a similar structure with the urokinase plasminogen activator receptor (11). Urokinase plasminogen activator receptor is expr...

Complement Receptor Mac-1 Is an Adaptor for NB1 (CD177)-mediated PR3-ANCA Neutrophil Activation

“…Purified recombinant human CD11b/CD18 integrin was from R&D systems (WiesbadenNordenstedt, Germany). NB1 and ␣IIb-␤3 was purified from human neutrophils or platelets as previously described (27,28). Endotoxin-free reagents and plastic disposables were used in all experiments.…”

A Hydrophobic Patch on Proteinase 3, the Target of Autoantibodies in Wegener Granulomatosis, Mediates Membrane Binding via NB1 Receptors

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“…Like membrane-bound PR3, neutrophil antigen NB1 shows variable expression on PMNs ranging from 0 to 100% (10). NB1, an as yet poorly characterized membrane receptor, appears to play a role in PMN transmigration as it interacts with PECAM-1 on endothelial cell membrane (14).…”

Engagement of αIIbβ3 (GPIIb/IIIa) with ανβ3 Integrin Mediates Interaction of Melanoma Cells with Platelets

“…Transmigration of B16 cells was performed as described previously (29,34). Briefly, transmigration assays were performed using 6.5-mm transwells with 8-m pore size (Costar, Bodenheim, Germany).…”