冯·维勒布兰特因素。

F Rodeghiero, G Castaman
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引用次数: 3

摘要

血管性血肿因子(vWf)是一种多聚体和多价粘附蛋白,对血小板粘附内皮下层和稳定循环中凝血因子VIII的促凝活性至关重要。vWf的定量测量基本上涉及两种不同的方法。第一种是基于vWf和血小板膜Gp - Ib在立斯托素存在下的相互作用(立斯托素辅助因子活性,RiCof),不仅取决于该因子的量,还取决于其产生这种相互作用的能力,大的多聚体更有活性。第二种方法涉及vWf (vWf:Ag)的免疫定量,通过其与特异性多克隆或单克隆抗体的相互作用,通过几种方法进行测量,即电免疫测定、免疫放射测定和免疫酶测定。虽然在大多数vWf功能失调的II型血管性血血病(vWd)中,RiCof与vWf:Ag存在差异,但需要强调的是,RiCof活性并不能完全反映vWf的“真实”活性,因为它并没有探索vWf的所有功能;此外,多元化程度与RiCof水平之间的关系并不总是成立的,例如在vWd“Vicenza”中。对于先天性和获得性vWd的诊断,RiCof检测和家族调查是合格的检测方法,估计能够检测到至少50%的异常基因携带者,包括轻度影响的患者;vWf:Ag似乎不太敏感,根据我们实验室进行的研究,建议的相对灵敏度为64%。两种检测方法都需要分别定义儿童和成人以及0和非0血型受试者的正常范围;建议在正常受试者的大样本中采用非参数方法。使用福尔马林固定血小板的聚合法进行RiCof测定,我们实验室发现高对照和低对照血浆的测定间变异性分别为6%和8.5%。用ELISA法测定vWf:Ag时,低对照血浆的变异率为7%,高对照血浆的变异率为6%。因此,这两种方法对于临床应用似乎都足够精确。根据国际标准校准的内部池的使用允许进行可比较的实验室间测量。为了进一步提高这些检测的标准化,似乎迫切需要合作研究。
本文章由计算机程序翻译,如有差异,请以英文原文为准。
The von Willebrand factor.

Von Willebrand factor (vWf) is a multimeric and multivalent adhesive protein which is essential for platelet adhesion to subendothelium and for stabilization of factor VIII procoagulant activity in circulation. The quantitative measurement of vWf involves essentially two different approaches. The first is based on the interaction between vWf and Gp Ib of the platelet membrane in presence of ristocetin (ristocetin cofactor activity, RiCof) and depends not only on the amount of the factor but also on its ability to bring about this interaction, large multimers being more active. The second approach involves the immunological quantitation of vWf (vWf:Ag) by its interaction with specific polyclonal or monoclonal antibodies as measured by several methods, i.e., electroimmunoassay, immunoradiometric assay and immunoenzymatic assay. Although in the majority of type II von Willebrand disease (vWd) with dysfunctional vWf there is a discrepancy between RiCof and vWf:Ag, it should be emphasized that RiCof activity does not entirely reflect the 'true' activity of vWf since it does not explore all the functions of this factor; furthermore, the relationship between degree of multimerization and RiCof level is not always tenable, as for example in vWd 'Vicenza'. For the diagnosis of congenital and acquired vWd RiCof assay together with family investigation is the eligible test, with an estimated ability to detect at least 50% of the carriers of the abnormal gene, including mildly affected patients; vWf:Ag appears less sensitive and, on the basis of studies carried out in our laboratory, a relative sensitivity of 64% is proposed. Both assays require the definition of separate normal ranges for children and adults and for 0 and non-0 blood group subjects; a nonparametric approach in a large sample of normal subjects is advisable. With RiCof assay performed by an aggregometric method using formalin-fixed platelets an interassay variability of 6% and 8.5% respectively for high- and low-control plasma was found in our laboratory. With vWf:Ag assayed by an ELISA method a variability of 7% for low- and 6% for high-control plasma was found. Thus, both methods appear sufficiently precise for clinical use. The use of an internal pool calibrated against an international standard allows to perform comparable interlaboratory measurements. To further improve standardization of these assays, collaborative studies seem urgently required.

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