Mannucci P M
Angelo Bianchi Bonomi Hemophilia and Thrombosis Center, IRCCS Maggiore Hospital, Milano, Italy.
Haemostasis. 1994 Sep-Oct;24(5):285-8. doi: 10.1159/000217115.
Therapeutic plasma concentrates containing von Willebrand factor (vWF) lack the largest, most hemostatically active multimers. In order to evaluate whether this abnormality results from proteolysis during manufacturing, we have analyzed the subunit structure of vWF in 21 commercial products and found a marked reduction in the relative content of intact 225 kD subunit, paralleled by an increase in the proteolytic fragments normally present in plasma, particularly that of 176 kD. There was no heightened vWF fragmentation in blood-bank cryoprecipitate prepared from platelet-poor, single-donor plasma; in contrast, there was a marked degree of fragmentation in cryoprecipitate prepared from pooled plasmapheresis plasma representing the starting fraction for the production of commercial concentrates. In cryoprecipitate prepared experimentally from plasma containing varying numbers of platelets, the degradation of vWF was proportional to the platelet count but was greatly diminished by adding protease inhibitors to plasma. On the basis of these findings, we postulate that the loss of the largest vWF multimers in commercial concentrates results from the use of poorly centrifuged plasmapheresis plasma containing an excessive number of residual platelets and leukocytes.
含有血管性血友病因子（vWF）的治疗性血浆浓缩物缺乏最大、止血活性最强的多聚体。为了评估这种异常是否源于生产过程中的蛋白水解作用，我们分析了21种商业产品中vWF的亚基结构，发现完整的225kD亚基的相对含量显著降低，与此同时，血浆中正常存在的蛋白水解片段，尤其是176kD片段有所增加。由少血小板单供体血浆制备的血库冷沉淀中，vWF的片段化程度并未增加；相反，由混合单采血浆制备的冷沉淀中出现了显著程度的片段化，而混合单采血浆是生产商业浓缩物的起始原料。在从含有不同数量血小板的血浆中实验性制备的冷沉淀中，vWF的降解与血小板计数成正比，但通过向血浆中添加蛋白酶抑制剂，降解程度大幅降低。基于这些发现，我们推测商业浓缩物中最大的vWF多聚体的缺失是由于使用了离心不充分的单采血浆，其中含有过多的残余血小板和白细胞。
