Thromb Haemost 2006; 96(06): 774-780
DOI: 10.1160/TH06-07-0367
Platelets and Blood Cells
Schattauer GmbH

Platelet microparticle formation and thrombin generation under high shear are effectively suppressed by a monoclonal antibody against GPIbα

Luca Pontiggia
1   Department of Medicine, Laboratory for Thrombosis Research, Kantonsspital Baden, Switzerland
,
Beat Steiner
2   Hoffmann-La Roche Ltd, Pharma Preclinical Research, Basel, Switzerland
,
Hans Ulrichts
3   Laboratory forThrombosis Research, IRC, KU Leuven, Campus Kortrijk, Belgium
,
Hans Deckmyn
3   Laboratory forThrombosis Research, IRC, KU Leuven, Campus Kortrijk, Belgium
,
Marc Forestier
1   Department of Medicine, Laboratory for Thrombosis Research, Kantonsspital Baden, Switzerland
,
Jürg H. Beer
1   Department of Medicine, Laboratory for Thrombosis Research, Kantonsspital Baden, Switzerland
› Author Affiliations
Financial support: Supported in part by the Swiss National Science Foundation, Grant-No. 32–59449.99 (JHB) Grant-No. 320080–104202 and the Swiss Heart Foundation (JHB).
Further Information

Publication History

Received 05 July 2006

Accepted after resubmission 17 October 2006

Publication Date:
29 November 2017 (online)

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Summary

We studied the inhibition of platelet microparticle (MP) formation and thrombin generation under high shear forces. We hypothesized that an inhibitor of the GPIbα-von Willebrand factor (vWF) interaction would be more effective in suppressing MP formation and thrombin generation than GPIIb/IIIa inhibitors. Platelet-rich plasma (PRP) anticoagulated with PPACK (D-Phe-Pro-Arg chloromethyl ketone) was exposed in a coneand-plate viscometer (shear: 5,000 s−1 for5 min) in the presence of antagonists to GPIbα (the monoclonal antibody [Mab] Ib-23) or to GPIIb/IIIa (abciximab, tirofiban, eptifibatide) at their IC90 determined in platelet aggregometry with ristocetin or ADP, respectively. We used double labeling (CD41-PE and annexin-V-FITC) for flow cytometric detection of MP and their aminophospholipid exposure. Thrombin generation was measured using PRP prepared fromACD anticoagulated blood. About 40% of the thrombin generation was found to be mediated by the MP fraction of the PRP. Blockade of GPIbα with Mab Ib-23 reduced MP formation and thrombin generation by 50%, and was more effective than any GPIIb/IIIa antagonist. The combination of Mab Ib-23 with one of the GPIIb/IIIa inhibitors further reduced the MP formation to ∼30%. The antibody also partially inhibited thrombin induced platelet aggregation. Epitope mapping suggested that Mab Ib-23 binds between the amino acids 201 and 268 of GPIbα, explaining the interference with vWF and thrombin interaction. In contrast to the commonly used GPIIb/IIIa antagonists, the blockade of GPIbα with Mab Ib-23 effectively reduces the prothrombotic MP generation and thrombin formation at shear rates typically found in arterial stenoses.

Footnote: Parts of this work were presented orally at the International Congress of Thrombosis and Hemostasis in Birmingham (2003), at the Meeting of the Swiss Society of Hematology in Basel, and as poster at the Meeting of the American Society of Hematology in San Diego (2003). Abstracts were published in Blood (2003); 102: 804a and in the Supplement to Thrombosis and Heamostasis, July 2003: OC465.