Previous studies have demonstrated that >38% of patients with immune-mediated thrombotic thrombocytopenic purpura in remission with activity >50% had an open ADAMTS13 (a disintegrin and metalloproteinase with thrombospondin type 1 motif, member 13) conformation. We assessed ADAMTS13 conformation in remission (ADAMTS13 activity >60%), focusing on peak ADAMTS13 activity levels and longitudinal assessment in 420 samples across 157 patients. Fewer cases had an open conformation at peak ADAMTS13 activity than unselected remission samples with ADAMTS13 activity >60% (23% vs 43%). Patients with a closed ADAMTS13 conformation at peak ADAMTS13 activity had an eightfold lower relapse rate in the subsequent year (9% vs 46%) and a fivefold lower relapse rate within 2 years (23% vs 62%) compared with cases with an open conformation. Patients with an open conformation at peak ADAMTS13 activity required preemptive anti-CD20 treatment earlier than those with a closed conformation (median, 10 vs 25 months). Longitudinally, an open conformation was evident at, and often preceded relapse. When the conformation was already open before relapse, an increase in the conformation index at relapse was seen despite the undetectable anti-ADAMTS13 immunoglobulin G (IgG) antibody. In cases with detectable anti-ADAMTS13 IgG antibody, these became undetectable before achieving a closed conformation, highlighting the relapse risk even with undetectable anti-ADAMTS13 IgG antibody and the clinical utility of open/closed during monitoring. To our knowledge, this is the first study to show an association between relapse risk and ADAMTS13 conformation when activity levels are at a peak. The open conformation identifies antibody-mediated subclinical disease that is not detectable by the current ADAMTS13 testing.
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http://dx.doi.org/10.1182/blood.2023023269 | DOI Listing |
Int J Lab Hematol
December 2024
LabPLUS, Auckland City Hospital, Auckland, New Zealand.
Introduction: The TECHNOSCREEN ADAMTS-13 assay (ADSC) is a new lateral flow test which is simple and quick to perform, with a high negative predictive value (NPV); it may improve the diagnostic workflow for TTP. LabPlus in Auckland, New Zealand, performs all ADAMTS13 tests in the Auckland and Northland regions. The ADSC was used at LabPlus between 2022 and 2023 as part of a protocol where results of 0 IU/mL and 0.
View Article and Find Full Text PDFAm J Clin Pathol
December 2024
Special Coagulation Laboratory, Division of Hematopathology, Department of Laboratory Medicine and Pathology, Mayo Clinic, Rochester, MN, US.
Objectives: Fluorescence resonance energy transfer (FRET)-based ADAMTS13 activity assays are critical for the diagnosis of thrombotic thrombocytopenic purpura. However, these assays are susceptible to interference. As iodide has been suggested to interfere in laboratory testing via fluorophore quenching or promotion, we aimed to determine whether iodinated contrast (Omnipaque) interferes with the ATS-13 ADAMTS13 Activity Assay 2.
View Article and Find Full Text PDFJ Thromb Haemost
December 2024
Department of Hematology, Nara Medical University, Kashihara, Japan; Department of Blood Transfusion Medicine, Nara Medical University, Kashihara, Japan. Electronic address:
Background: Thrombotic thrombocytopenic purpura (TTP) is a fatal disease caused by severe deficiency in ADAMTS13 activity. ADAMTS13 activity measurement is essential for the diagnosis of TTP, but conventional standard assays are manual and time-consuming. Automated ADAMTS13 activity assays have recently become available; however, their accuracy remains challenging.
View Article and Find Full Text PDFRes Pract Thromb Haemost
October 2024
Department of Pathology and Laboratory Medicine, University of Kansas Medical Center, Kansas City, Kansas, USA.
TH Open
October 2024
Thrombosis and Haemostasis Unit, Hospital de la Santa Creu i Sant Pau, Barcelona, Spain.
Association between global platelet function and the risk of venous thromboembolic disease (VTE) has been proposed, though the mechanisms do not involve increased platelet aggregation. However, platelet adhesiveness has not been systematically explored in VTE patients. To evaluate platelet adhesive functions in VTE patients.
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