Abstract Number: PB1453
Meeting: ISTH 2020 Congress
Background: The role of granulocytes in thrombus formation and their interaction with platelets in normal and thrombocytopenic states are not fully understood and have been the focus of recent research.
Aims: Observation of thrombus formation and granulocyte activity in whole blood of normal and thrombocytopenic subjects in parallel-plate flow chambers (ex vivo).
Methods: Whole hirudinated blood of healthy pediatric donors (n=12) or pediatric patients with Wiskott-Aldrich syndrome (WAS; n=7), immune thrombocytopenia (ITP; n=4), Glanzmann thrombastenia (GT; n=4), MYH-9 linked macrothrombocytopenia (MYH-9; n=4), ANKRD26-associated thrombocytopenia (ANKRD26; n=2) was used in the experiments within 3 hours of blood collection. The samples were perfused through parallel-plate flow chambers coated with fibrillar collagen type I. Platelet aggregate formation and CD66b-positive cell activity were assessed by low-angle fluorescent and DIC microscopy. Numerical analysis of the images was performed in ImageJ software and a developed for this study Python 3.7 application.
Results: Formation of platelet aggregates and granulocytes’ movement were observed simultaneously on the flow chamber surface. The movement of granulocytes appeared to occur along the collagen fibrils towards platelet aggregates. Collection of procoagulant platelets by granulocytes was frequently observed. The following criteria were derived: number of leukocytes per field of view (NL), leukocyte crawling velocity (VL), thrombus area (A), ratio of NL to A (RAN), percentage of spread leukocytes (S). All of the patients had decreased A (as expected) and increased S. NL in patients with ITP, MYH9 and GT was significantly lower than in control group. VL was significantly lower in WAS, ITP and MYH9. RAN was higher than control in WAS, GT and MYH9.
Conclusions: During thrombus formation platelet-granulocyte interaction is characterized by neutrophil chemostaxis to activated platelets and their scavenging of procoagulant platelets. The relative activity of granulocytes in thrombi was generally higher in patients with thrombocytopenic disorders in comparison with healthy controls.
To cite this abstract in AMA style:Morozova D, Martyanov A, Fedorova D, Zharkov P, Panteleev M, Shcherbina A, Sveshnikova A. Ex vivo Observation of Platelet-granulocytes Interactions in Pediatric Patients with Congenital Platelet Defects [abstract]. Res Pract Thromb Haemost. 2020; 4 (Suppl 1). https://abstracts.isth.org/abstract/ex-vivo-observation-of-platelet-granulocytes-interactions-in-pediatric-patients-with-congenital-platelet-defects/. Accessed October 21, 2021.
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