Mikaelsson M, Oswaldsson U, Sandberg H
Recombinant Factor VIII, R&D, Pharmacia & Upjohn AB, Stockholm, Sweden.
Haemophilia. 1998 Jul;4(4):646-50. doi: 10.1046/j.1365-2516.1998.440646.x.
In view of reported discrepancies between different factor VIII assays, the influence of phospholipids on the performance of one-stage clotting (OS) and chromogenic substrate (CS) assays was evaluated. The B domain deleted recombinant factor VIII, rVIII SQ, two full-length recombinant products and a plasma derived factor VIII concentrate were each diluted into severe haemophilia A plasma and assayed against a plasma standard. The one-stage activity was 50, 80, 75 and 106%, respectively, of the chromogenic result. Variations in the phospholipid concentration did not affect the chromogenic assay, except at very low levels where the apparent activity increased. In contrast, dilution of the phospholipid reagent had a substantial influence on the activity measured by OS assays, especially in the case of rVIII SQ. At low levels of phospholipid, the one-stage activity of rVIII SQ exceeded the chromogenic result. When mixtures of phosphatidylserine (PS) and phosphatidyl-choline (PC) were used as a source of phospholipid, the OS results for rVIII SQ agreed well with the CS activity as long as the content of PS was below 10%, i.e., closer to the physiological level. At higher levels of PS, as in most commercial APTT reagents, the OS activity decreased. When the APTT reagent was replaced by platelets in the OS assay, the results compared well with those obtained by the CS assay for both t-VIII SQ and full-length factor VIII products.
鉴于不同的凝血因子VIII检测方法之间存在报道的差异，评估了磷脂对一期凝血（OS）和发色底物（CS）检测性能的影响。将缺失B结构域的重组凝血因子VIII、rVIII SQ、两种全长重组产品和一种血浆源性凝血因子VIII浓缩物分别稀释到重度甲型血友病血浆中，并与血浆标准品进行检测。一期活性分别为发色法结果的50%、80%、75%和106%。磷脂浓度的变化对发色法检测没有影响，除非在非常低的水平下，表观活性会增加。相反，磷脂试剂的稀释对OS检测所测活性有很大影响，尤其是对于rVIII SQ。在低磷脂水平下，rVIII SQ的一期活性超过发色法结果。当使用磷脂酰丝氨酸（PS）和磷脂酰胆碱（PC）的混合物作为磷脂来源时，只要PS含量低于10%，即更接近生理水平，rVIII SQ的OS结果与CS活性就非常吻合。在较高的PS水平下，如大多数商业活化部分凝血活酶时间（APTT）试剂中那样，OS活性会降低。当在OS检测中用血小板替代APTT试剂时，对于t-VIII SQ和全长凝血因子VIII产品，其结果与CS检测获得的结果相比良好。
