23 research outputs found
Large experience with a factor VIII binding assay of plasma von Willebrand factor using commercial reagents
Heparin Binding Assay of von Willebrand Factor (vWF) in Plasma Milieu – Evidence of the Importance of the Multimerization Degree of vWF
Improved Characterization of Plasma von Willebrand Factor Heterogeneity when Using 2.5% Agarose Gel Electrophoresis
Functional and Immunological Assays of F VIII in 133 Haemophiliacs - Characterization of a Subgroup of Patients with Mild Haemophilia A and Discrepancy in 1- and 2-Stage Assays
Estimation of the Carbohydrate Moiety of von Willebrand Factor in the Plasma of Patients with Subtypes 2a and 2b of von Willebrand Disease
Measurement of von Willebrand factor binding to a recombinant fragment of glycoprotein Ibalpha in an enzyme-linked immunosorbent assay-based method: performances in patients with type 2B von Willebrand disease
Type 2B von Willebrand disease (VWD) is characterised by an increased affinity of von Willebrand factor (VWF) for its platelet receptor glycoprotein Ib (GPIb). This feature is usually studied in vitro by a ristocetin-dependent VWF platelet-binding assay, which has some limitations as it requires [e.g. (radio)-labelled anti-VWF antibodies and normal formaldehyde-fixed platelets]. We, here, extended the applicability of an enzyme-linked immunosorbent assay-based method previously described for the measurement of ristocetin co-factor activity that used a recombinant fragment of GPIb (rfGPIb alpha) and horseradish peroxidase-labelled rabbit anti-human VWF antibodies for measuring the captured ristocetin-VWF complexes on the rfGPIb alpha. Thirty-one type 2B VWD patients from 15 families with eight different known mutations were studied. VWF in plasma from 28 of these patients bound better than normal VWF at 0.2 mg/ml ristocetin, with the ratio, optical density (OD) patient/OD normal pool plasma, higher than 1.8. For two of the three other patients with no enhanced response of plasma VWF, the platelet lysate VWF showed an enhanced binding capacity; for the last patient, the results in other members of the family are unequivocal. We conclude that, this new method for measurement of plasma or platelet VWF-binding capacity offers great advantages for correct type 2B VWD diagnosis.status: publishe