Fondazione IRCCS Ca' Granda Ospedale Maggiore Policlinico, Angelo Bianchi Bonomi Hemophilia and Thrombosis Center, Milan, Italy.
Department of Pathophysiology and Transplantation, Università degli Studi di Milano, Milan, Italy.
Methods Mol Biol. 2023;2663:669-677. doi: 10.1007/978-1-0716-3175-1_44.
von Willebrand disease (VWD) is a lifelong and common inherited bleeding disorder caused by a quantitative deficiency and/or qualitative defect of von Willebrand factor (VWF). In order to establish the correct diagnosis of VWD, various tests must be conducted, including evaluation of factor VIII activity (FVIII:C), VWF antigen (VWF:Ag), and VWF functional activity. The platelet-dependent VWF activity is measured in different ways, with the historical ristocetin cofactor assay (VWF:RCo) using platelet aggregometry now replaced with newer assays that offer better precision, lower limits of detection, low coefficient of variation, and are fully automated. The VWF activity by glycoprotein Ib-binding assays (VWF:GPIbR) measured on the ACL TOP platform represents an automated assay that instead of using platelets employs latex beads coated with recombinant wild-type GPIb. VWF in the test sample agglutinates the polystyrene beads coated with GPIb in the presence of ristocetin. The reduction of turbidity as beads agglutinate represents a linear relationship with VWF:GPIbR activity. Using a ratio of VWF:GPIbR/VWF:Ag, the VWF:GPIbR assay also provides good sensitivity and specificity for distinguishing type 1 VWD from type 2. The following chapter describes a detailed protocol for the VWF:GPIbR assay.
血管性血友病（VWD）是一种终身性和常见的遗传性出血性疾病，由血管性血友病因子（VWF）的数量缺乏和/或质量缺陷引起。为了建立 VWD 的正确诊断，必须进行各种测试，包括因子 VIII 活性（FVIII:C）、VWF 抗原（VWF:Ag）和 VWF 功能活性的评估。血小板依赖性 VWF 活性以不同的方式测量，历史上使用血小板聚集仪的瑞斯托霉素辅因子测定（VWF:RCo）现已被提供更好的精度、更低检测限、低变异系数且完全自动化的新型测定方法所取代。ACL TOP 平台上的糖蛋白 Ib 结合测定（VWF:GPIbR）测量的 VWF 活性代表一种自动化测定方法，该方法不使用血小板，而是采用包被有重组野生型 GPIb 的乳胶珠。在瑞斯托霉素存在的情况下，测试样品中的 VWF 凝集包被有 GPIb 的聚苯乙烯珠。随着珠粒凝集，浊度的降低与 VWF:GPIbR 活性呈线性关系。使用 VWF:GPIbR/VWF:Ag 的比值，VWF:GPIbR 测定还为区分 1 型 VWD 和 2 型提供了良好的敏感性和特异性。以下章节详细描述了 VWF:GPIbR 测定的方案。
