Bangham D R, Biggs R, Brozović M, Denson K W, Skegg J L
Bull World Health Organ. 1971;45(3):337-51.
Because of the instability of Factor VIII (antihaemophilic factor) in plasma in vitro, and since evidence has accumulated that the level of activity varies significantly between samples of "fresh normal plasma", it is apparent that a stable biological standard is required.Two freeze-dried preparations of Factor VIII, one plasma and one concentrate preparation, were prepared and have been assayed in a collaborative trial by 20 laboratories in 9 countries.The laboratories used their own methods and altogether 248 assays were carried out. Comparison of materials of similar type gave precise estimates with all the methods used, but when materials dissimilar in type and in Factor VIII content were compared less precise results were obtained. Sources of variation, such as differences in method, differences between operators, and day-to-day variations, were analysed.Accelerated degradation tests, carried out on the freeze-dried plasma and concentrate preparations, showed that Factor VIII activity was sufficiently stable in the concentrate for it to be used as a long-term standard but that the Factor VIII activity was less stable in the plasma preparation.
由于凝血因子VIII（抗血友病因子）在体外血浆中不稳定，而且越来越多的证据表明，“新鲜正常血浆”样本之间的活性水平差异显著，显然需要一种稳定的生物标准品。制备了两种凝血因子VIII冻干制剂，一种是血浆制剂，一种是浓缩制剂，并在9个国家的20个实验室进行的协作试验中进行了测定。各实验室使用自己的方法，共进行了248次测定。对相似类型的材料进行比较时，使用的所有方法都给出了精确的估计值，但当比较类型和凝血因子VIII含量不同的材料时，得到的结果不太精确。分析了变异来源，如方法差异、操作人员之间的差异以及日常变异。对冻干血浆和浓缩制剂进行的加速降解试验表明，凝血因子VIII活性在浓缩制剂中足够稳定，可以用作长期标准品，但在血浆制剂中凝血因子VIII活性不太稳定。
