PB1365 - Serum complement levels in adult patients with primary immune thrombocytopenia

Tuesday, June 27, 2023

18:30 – 19:30 ET

Room: Exhibition

Presenting Author(s)

Jasmin Rast, MD

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

Co-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
Dino Mehic, MD

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

Thomas Perkmann

MD
Department of Laboratory Medicine, Medical University of Vienna, Vienna, Austria.
Vienna, Wien, Austria
MF

Michael Filitz

MD
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
Cihan Ay, MD (he/him/his)

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 (she/her/hers)

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

Background: The activation of the complement system in patients with primary immune thrombocytopenia (ITP) is one proposed mechanism of increased platelet destruction and complement inhibition is a new treatment target in ITP.

Aims: To investigate C3c, C4, CH50 levels in primary ITP patients and their association with clinical and hematological phenotype.

Methods: Serum levels of C3c, C4, CH50 were analyzed in adult patients with primary ITP included in the Vienna ITP Biobank and 25 healthy controls (HC) (EC1843/2016) at study inclusion on a BN™ II nephelometer (C3c, C4, Siemens Healthcare Diagnostics, Marburg, Germany) and by the liposome-based Fujifilm Autokit test (CH50, Fujifilm Wake Chemicals, Neuss, Germany) on a cobas6000 analyzer (Roche Diagnostics, Switzerland).

Results: A total of 118 ITP patients were included, of whom 33 patients (27.9%) had acute ITP, 11 (9.3%) had persistent ITP and 74 (62.7%) had chronic ITP. Patient characteristics and complement levels are shown in Table 1. Compared to HC, ITP patients had lower levels of C3c (P=.014) and C4 (P=.017) both, in the subgroup of acute ITP (C3c: P = .007; C4: P=.005) and chronic ITP (C3c: P=.018; C4: P =.019), Figure 1A-B. All patients and 21 HC (84%) had CH50 levels above the reference range of 31,6–57,6 U/ml. C3c levels, but not C4, correlated weakly with the platelet count (r=.231, P.022), but no significant correlation of any complement parameter and mean platelet volume (MPV) or immature platelet fraction (IPF) was seen. None of the complement parameters correlated with bleeding severity (assessed with the ITP SMOG). No significant difference in complement levels was seen between patients with and without antiplatelet antibodies, current treatment, previous splenectomy, current bleeding or previous thrombotic event.

Conclusion(s): Our data indicate that adult primary ITP patients have lower C3c and C4 complement levels than healthy persons. No relevant correlation with clinical or laboratory parameters was seen.