Back
A MONOCLONAL ANTIBODY AGAINST PLATELET GPIBBETA INHIBITS GPIB-V-IX-DEPENDENT SIGNALLING, PROCOAGULANT ACTIVITY AND THROMBUS FORMATION UNDER FLOW PERFUSION
Abstract number: P-W-257
Mangin1 P., Strassel1 C., Ravanat1 C., Kleitz1 L., Cazenave1 J.P., Gachet1 C., Lanza1 F.
1INSERM U.311, EFS-Alsace, Strasbourg, France
How-to-cite Mangin P, Strassel C, Ravanat C, Kleitz L, Cazenave JP, Gachet C, Lanza F. A MONOCLONAL ANTIBODY AGAINST PLATELET GPIBBETA INHIBITS GPIB-V-IX-DEPENDENT SIGNALLING, PROCOAGULANT ACTIVITY AND THROMBUS FORMATION UNDER FLOW PERFUSION. J Thromb Haemost 2007; 5 Supplement 2: P-W-257
Abstract
Introduction: RAM.1, a rat monoclonal antibody directed against the extracellular domain of GPIbb, has been reported to inhibit platelet adhesion to von Willebrand factor (VWF) under flow conditions. In this study we evaluated the potential of RAM.1 to inhibit GPIb-V-IX induced signalling, platelet procoagulant activity and thrombus formation in vitro.
Methods: Filopodia extension, used as a marker of GPIb signalling, was quantified in human platelets and GPIb-IX transfected CHO cells adhering to a VWF matrix. PLCg2 phosphorylation was evaluated in lysates from platelets agglutinated by VWF. Procoagulant activity was measured with the Calibrated Automated Thrombin Generation (CAT) method. Thrombus formation was evaluated by fluorescence video-microscopy following perfusion (750 s-1 to 3,000 s-1) of hirudinated blood from C57/Bl6 mice over a collagen matrix.
Results: RAM.1 (10 mg/ml) inhibited by 80% platelet and CHO-GPIb-IX cell filopodia extension following adhesion to a VWF matrix, without significantly affecting the number of adherent cells. RAM.1 also dramatically reduced the level of PLCg2 phosphorylation when platelets were agglutinated with VWF. RAM.1 inhibited by 25% and 30% the generation of thrombin, when PRP was stimulated with collagen (10 mg/ml) or tissue factor (0.5 pM), respectively. In an in vitro flow perfusion assay, RAM.1 (10 mg/ml) exhibited shear selective inhibition of thrombus formation following mouse blood perfusion over a collagen matrix. Thrombus size was strongly decreased at pathological wall shear rates (~75% inhibition) whereas it was less severely reduced under arterial (44% inhibition) and venous shear conditions (40% inhibition).
Conclusions: Altogether, these results confirm a role for GPIbb in GPIb-V-IX induced signalling and suggest a role in platelet procoagulant activity which could contribute to thrombus formation in pathological settings. Blockade of GPIbb could represent a novel interesting anti-thrombotic strategy directed against the GPIb-V-IX complex.
To cite this abstract use the following format:
Journal of Thrombosis and Haemostasis 2007; Volume 5, Supplement 2: abstract number
Session Details
| Date: |
01/08/2007
|
| Time: |
00:00-00:00
|
| Session name: |
XXIst ISTH Congress |
| Subject: |
|
| Location: |
Oxford, UK |
| Presentation type: |
|
| Back to top |
|
