PB0663 - Platelet desialylation in adults with primary immune thrombocytopenia

Monday, June 24, 2024

13:45 – 14:45 ICT

Room: Exhibition Hall

Presenting Author(s)

Theresa Schramm, MSc

PhD Student
Division of Hematology and Hemostaseology, Department of Medicine I, Medical University of Vienna
Vienna, Wien, Austria

Co-Author(s)

Jan Zlamal

MD
Institute for Clinical and Experimental Transfusion Medicine, University Hospital of Tuebingen, Germany
Tuebingen, Baden-Wurttemberg, Germany
Jasmin Rast

PhD Student/MD
Division of Hematology and Hemostaseology, Department of Medicine I, Medical University of Vienna
Vienna, Wien, Austria
MF

Michael Fillitz

Medical Doctor
Department of Internal Medicine, Hanusch Krankenhaus
Vienna, Wien, Austria
Dino Mehic

PhD Student/MD
Division of Hematology and Hemostaseology, Department of Medicine I, Medical University of Vienna
Vienna, Wien, Austria
Cihan Ay, MD

Professor
Division of Hematology and Hemostaseology, Department of Medicine I, Medical University of Vienna
Vienna, Wien, Austria
Ingrid Pabinger

Professor
Division of Hematology and Hemostaseology, Department of Medicine I, Medical University of Vienna
Vienna, Wien, Austria
Karina Althaus, MD

MD
Center for Clinical Transfusion Medicine, University Hospital Tuebingen
Tuebingen, Baden-Wurttemberg, Germany
Tamam Bakchoul, Professor MD

Medical Director
Center for Clinical and Experimental Transfusion Medicine, University Hospital of Tuebingen
Tuebingen, Baden-Wurttemberg, Germany
Johanna Gebhart

Assoc. Professor
Department of Internal Medicine I, Clinical Division of Hematology and Haemostaseology, Medical University of Vienna
Vienna, Wien, Austria

Background: Platelet desialylation is one pathomechanism in immune thrombocytopenia (ITP). Sialic acid cleavage exposes galactose residues and marks platelets for Fc-independent clearance.

Aims: To elucidate the incidence of platelet desialylation and its association with ITP disease phenotype in a large and well-characterized cohort of adult primary ITP patients.

Methods: Adult primary ITP patients from the Vienna ITP Biobank (EC 1843/2016) were investigated. A lectin binding assay was performed as previously described in Marini et al 2019. Therein exposure of beta-Galactose and N-Acetylglucosamine on platelets was analyzed by flow cytometry. AAb specificity was elucidated via the specific platelet antibodies assay (SASPA).

Results: In total 147 ITP patients (26% newly diagnosed, 74% chronic) were investigated (Tab.1). Forty patients (27%) had platelet desialylation with only beta-Galactose exposure in 16 (32.5%), N-Acetylglucosamine exposure in 13 (40.0%), and exposure of both in 11 (27.5%). Overall, 27 patients (18.4%) exposed N-Acetylglucosamine, and 24 (16.3%) beta-Galactose (Fig.1A, Tab.1).
AAbs against GPIIbIIIa and/or GPIbIX were found in 46 patients (33.8%). Anti-GPIIbIIIa and/or anti-GPIbIX AAbs detection was more common in patients with platelet desialylation (19, 50%) compared to those without desialylating Abbs (27, 27.6%, p=0.013) (Tab.1). AAbs against GPIbIX, GPIIbIIIa, and both were detected in 40%, 32%, and 29% of patients with exposure of N-Acetylglucosamine, and 20%, 27% and 0% with beta-Galactose exposure (Fig.1B-C). No AAbs were detected in 12% and 14%, respectively.
Thrombopoietin levels were higher in patients with desialylating AAbs, whereas there was no difference in platelet counts, the bleeding score, disease duration, and other ITP characteristics (Tab.1).

Conclusion(s): Platelet desialylation occurred in 27% of adult primary ITP patients, and was associated with positivity for AAbs against GPIbIX and GPIIbIIIa. In contrast to previous data, we could not confirm an association of platelet desialylation with platelet counts, bleeding severity, disease duration, or other ITP related clinical factors.