title: The von Willebrand factor collagen-binding activity assay: clinical application.
abstract: A collagen type III based collagen-binding assay was developed for measuring the functional activity of the von Willebrand factor. The assay had a low coefficient of variance (4.8%) for normal values under optimized conditions. The results of the collagen-binding activity (CBA) assay correlated with ristocetin cofactor activity tested in normal plasma samples (n=29). We found that the CBA of blood group O is lower than that of other blood groups. The test was used for the diagnosis of von Willebrand's disease (VWD) and for estimating the response to treatment with DDAVP (1-deamino-D-arginine-8 vasopressin) and factor VIII concentrate. A mean ratio of VWF antigen (VWF:Ag) to CBA of 1.5 indicated type 1 and of 2.7 indicated type 2 VWD. The increase in the collagen-binding activity of VWF released in type 1 VWD patients (n=7) after treatment with DDAVP was higher than the increase in the VWF antigen; this is characteristic of very high multimers with greater functional activity. Factor VIII concentrate Koate-HP (Bayer) administered to a patient with VWD type 3 had a mean residence time of 12.6 h for VWF:Ag and 11.2 h for CBA. These findings suggest that the collagen-binding assay is a useful test for measuring the functional activity of VWF in plasma samples, factor VIII concentrates, as well as for estimating the outcome of treatment.
authors.affiliation: Department of Pharmacy, University of Tartu, Estonia. Ade.Kallas@kliinikum.ee
authors.forename: A
authors.initials: A
authors.lastname: Kallas
authors.forename: T
authors.initials: T
authors.lastname: Talpsep
mesh_terms: D003094:Collagen / Q000378:metabolism*; D003894:Deamino Arginine Vasopressin / Q000627:therapeutic use; D004797:Enzyme-Linked Immunosorbent Assay / Q000379:methods; D005167:Factor VII / Q000627:therapeutic use; D006801:Humans; D012016:Reference Values; D014842:von Willebrand Diseases / Q000175:diagnosis / Q000188:drug therapy; D014841:von Willebrand Factor / Q000032:analysis / Q000378:metabolism*
chemical_list: D014841:von Willebrand Factor; D005167:Factor VII; D003094:Collagen; D003894:Deamino Arginine Vasopressin