PB1212 - Platelet desialylation status in adults with primary immune thrombocytopenia

Tuesday, July 12, 2022

6:30 PM – 7:30 PM

Location: Exhibition

Presentation Format: In-Person

Presenting Author(s)

Theresa Schramm, MSc

PhD Student
Department of Medicine I, Clinical Division of Haematology and Haemostaseology; Medical University of Vienna, Vienna, Austria
Vienna, Wien, Austria

Co-Author(s)

CU

Caroline Ungerböck

MD/PhD Candidate
Department of Medicine I, Clinical Division of Haematology and Haemostaseology, Medical University of Vienna, Vienna, Austria
Vienna, Wien, Austria
MF

Michael Fillitz

Senior Physician
Department of Internal Medicine, Hanusch Krankenhaus, Vienna, Austria
Vienna, Wien, Austria
BD

Barbara Dixer

Chief Study Coordinator
Department of Internal Medicine, Hanusch Krankenhaus, Vienna, Austria,
Vienna, Wien, Austria
DM

Dino Mehic, MD

Resident physician
Clinical Division of Hematology and Hemostaseology, Department of Medicine I, Medical University of Vienna, Vienna, Austria
Vienna, Wien, Austria
Tamam Bakchoul, MD

Medical Director
Center for Clinical Transfusion Medicine, University Hospital of Tübingen
Tübingen, Baden-Wurttemberg, Germany
IM

Irene Marini

PhD
Center for Clinical Transfusion Medicine
Tübingen, Baden-Wurttemberg, Germany
Jan Zlamal

Resident/PhD Student
Institute for clinical and experimental transfusion medicine Tübingen
Tübingen, Baden-Wurttemberg, Germany
Cihan Ay, MD

Professor, Head of the Thrombosis and Haemostasis Research Group
Clinical Division of Haematology and Haemostaseology, Department of Medicine I, Medical University of Vienna, Vienna, Austria
Vienna, Wien, Austria
Ingrid Pabinger, MD

Co-Head of the Thrombosis and Haemostasis Research Group
Clinical Division of Hematology and Hemostaseology, Department of Medicine I, Medical University of Vienna, Vienna, Austria
Vienna, Wien, Austria
Johanna Gebhart, MD, PhD

Ap. Prof. Dr. PhD
Clinical Division of Hematology and Hemostaseology, Department of Medicine I, Medical University of Vienna, Vienna, Austria
Vienna, Wien, Austria

Background: In primary immune thrombocytopenia (ITP), patients express heterogeneous bleeding phenotypes and partially increased thromboembolic risk. Autoantibodies (AAbs) can induce platelet desialylation, leading to platelet clearance. A high level of platelet desialylation is observed in refractory ITP, whereas its impact on bleeding phenotype and thrombosis incidence is not completely elucidated yet.

Aims: To identify the effect of desialylated platelets on the clinical phenotype in respect to bleeding or thrombosis in adults with primary ITP.

Methods: Samples of a characterized cohort of 86 adult primary ITP patients and 20 healthy controls (HC) from the Vienna ITP Biobank (EC 1843/2016) were investigated. Platelet desialylation was assessed via a lectin binding assay: washed platelets from healthy individuals were incubated with patient or HC serum and stained with erythrina cristagalli lectin (ECL) or ricinus communis agglutinin (RCA) followed by flow cytometric analysis. Mean fluorescence intensity (MFI) cutoffs (ECL: MFI=1.43; RCA: MFI=1.10) were calculated based on HCs.

Results: 86 ITP patients were investigated in this study. 9 patient sera (10.5%) induced significant platelet desialylation with increased binding of ECL and/or RCA to platelets (3 ECL only, 4 RCA only, 2 ECL and RCA, Figure 1). Subsequent analysis of ITP AAb glycoprotein specifities revealed that 1 patient presented with AAbs against platelet GPIIb/IIIa and 5 without detectable ITP AAbs. The AAb status was not known in 3 patients. The 2 patients with binding of both lectins presented with chronic ITP and did not have detectable AAbs against GPIIb/IIIa or GPIb/IX. There were no significant differences in relevant clinical characteristics, bleeding severity, or previous thrombosis history between patients with and without platelet desialylation (Table 1).

Conclusion(s): Desialylation was observed in 10.5% of the investigated patient population and mainly restricted to patients with chronic ITP. No association of platelet desialylation with multi-refractory ITP, the bleeding phenotype or thrombosis history was detected.