Intravenous immunoglobulin prevents thrombosis in an endothelialized disease model of heparin-induced thrombocytopenia
Andreas Witzemann 1); Günalp Uzun 1),2); Nina Wolska 1); Meltem Avci-Adali 3); Jean Amiral 4); Karina Althaus 1),2); Tamam Bakchoul 1),2); Jan Zlamal 1),2)
1 – Institute for Clinical and Experimental Transfusion Medicine, Medical Faculty of Tübingen, University of Tübingen, Tübingen, Germany
2 – Centre for Clinical Transfusion Medicine, Tübingen, Germany
3 – Hemostasis and Thrombosis Diagnostics, Franconville, France
4 – Department of Thoracic and Cardiovascular Surgery, University Hospital Tübingen, Tübingen, Germany
Abstract
Background
Heparin-induced thrombocytopenia (HIT) is a serious adverse reaction to heparin, associated with increased risk of thromboembolic complications. Intravenous immunoglobulins (IVIGs) have been used as a therapeutic for HIT and are believed to alleviate thrombocytopenia and reduce thrombosis risk. Yet the antithrombotic effects of IVIG in HIT remain underexplored.
Objective
To investigate the effect of IVIG on thrombus formation in an ex vivo model of HIT–IgG-induced thrombosis.
Methods
Microfluidic channels were coated with a confluent monolayer of human umbilical vein endothelial cells that were primed with TNF-α to induce an activated, inflammatory state. Whole blood was exposed to unfractionated heparin, with or without IVIG before subjecting to treatment with a monoclonal HIT-like antibody (K070), or HIT-patient–IgG. Recalcified blood was perfused over human umbilical vein endothelial cells at venous shear stress. Thrombus structure and dynamics were investigated by immunofluorescence microscopy.
Results
HIT-patient–IgGs and K070 induced thrombus formation in the presence of prophylactic heparin exposure, over TNF-α treated, inflamed endothelial cells. HIT thrombi were enriched in fibrin, phosphatidylserine-bearing platelets, and leukocyte aggregates. We observed thrombi being formed on adherent platelets, which gradually recruited leukocytes into a three-dimensional thrombus structure. Pretreatment of blood with IVIG significantly reduced cellular adhesions and prevented thrombus formation.
Conclusion
Our endothelialized ex vivo flow chamber system effectively recapitulates the immunothrombotic phenotype of HIT and offers a reliable tool to urgently validate the efficacy of IVIG intervention against HIT–IgG-induced thrombosis in patients.