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A novel flow-based assay reveals discrepancies in ADAMTS-13 inhibitor assessment as compared with a conventional clinical static assay.
- Source :
-
Journal of thrombosis and haemostasis : JTH [J Thromb Haemost] 2014 Sep; Vol. 12 (9), pp. 1523-32. Date of Electronic Publication: 2014 Jul 29. - Publication Year :
- 2014
-
Abstract
- Background: Several static Bethesda-type assays are routinely used to determine ADAMTS-13-neutralizing autoantibodies in acquired thrombotic thrombocytopenic purpura (TTP), but the inhibitory activity of these antibodies has not been thoroughly evaluated under the more physiologic condition of flow.<br />Objectives: We investigated whether ADAMTS-13 inhibitor assessment with the FRETS-VWF73 assay is predictive for evaluation under flow.<br />Methods: Anti-ADAMTS-13 autoantibodies were purified from patients with acquired TTP by chromatography involving an ADAMTS-13 affinity matrix and/or protein G. ADAMTS-13 activity was measured with the FRETS-VWF73 assay and a novel flow assay determining the ADAMTS-13-mediated decrease in platelet aggregate surface coverage, caused by perfusion of a suspension containing platelets, erythrocytes and von Willebrand factor (VWF) over a surface coated with extracellular matrix components. The neutralizing activities of ADAMTS-13 inhibitors were compared under static conditions and under flow by use of the two assays.<br />Results: The suitability of the flow-based ADAMTS-13 activity assay for quantification of ADAMTS-13 inhibitors could be demonstrated by reversibility of the ADAMTS-13-dependent decrease in surface coverage upon addition of goat ADAMTS-13 antiserum. Testing the neutralizing activity of purified autoantibodies from six patients in the flow assay according to their FRETS-VWF73-based inhibitor titers gave rise to vastly different inhibitory effects, indicating a discrepancy in inhibitor assessment between static and flow conditions.<br />Conclusions: Anti-ADAMTS-13 autoantibodies may show inhibitory properties in vivo that are not consistent with the ADAMTS-13 inhibitor levels determined in routine static assays, possibly because certain epitopes are selectively exposed under shear. Consequently, the course of disease and treatment efficacy may vary among TTP patients, despite common inhibitor titers.<br /> (© 2014 International Society on Thrombosis and Haemostasis.)
- Subjects :
- ADAMTS13 Protein
Blood Coagulation Tests methods
Cytoskeletal Proteins chemistry
Fluorescence Resonance Energy Transfer
Humans
Immunoglobulin G chemistry
LIM Domain Proteins chemistry
Platelet Aggregation
Protein Binding
Purpura, Thrombotic Thrombocytopenic diagnosis
RNA-Binding Proteins
Shear Strength
Stress, Mechanical
von Willebrand Factor chemistry
ADAM Proteins chemistry
ADAM Proteins immunology
Autoantibodies chemistry
Blood Coagulation Tests instrumentation
Hematologic Tests methods
Purpura, Thrombotic Thrombocytopenic blood
Subjects
Details
- Language :
- English
- ISSN :
- 1538-7836
- Volume :
- 12
- Issue :
- 9
- Database :
- MEDLINE
- Journal :
- Journal of thrombosis and haemostasis : JTH
- Publication Type :
- Academic Journal
- Accession number :
- 25040659
- Full Text :
- https://doi.org/10.1111/jth.12653