Cawthern K M, van 't Veer C, Lock J B, DiLorenzo M E, Branda R F, Mann K G
Department of Biochemistry, College of Medicine, University of Vermont, Burlington, VT 05405-0068, USA.
Blood. 1998 Jun 15;91(12):4581-92.
Tissue factor (TF)-induced coagulation was compared in contact pathway suppressed human blood from normal, factor VIII-deficient, and factor XI-deficient donors. The progress of the reaction was analyzed in quenched samples by immunoassay and immunoblotting for fibrinopeptide A (FPA), thrombin-antithrombin (TAT), factor V activation, and osteonectin. In hemophilia A blood (factor VIII:C <1%) treated with 25 pmol/L TF, clotting was significantly delayed versus normal, whereas replacement with recombinant factor VIII (1 U/mL) restored the clot time near normal values. Fibrinopeptide A release was slower over the course of the experiment than in normal blood or hemophilic blood with factor VIII replaced, but significant release was observed by the end of the experiment. Factor V activation was significantly impaired, with both the heavy and light chains presenting more slowly than in the normal or replacement cases. Differences in platelet activation (osteonectin release) between normal and factor VIII-deficient blood were small, with the midpoint of the profiles observed within 1 minute of each other. Thrombin generation during the propagation phase (subsequent to clotting) was greatly impaired in factor VIII deficiency, being depressed to less than 1/29 (<1.9 nmol TAT/L/min) the rate in normal blood (55 nmol TAT/L/min). Replacement with recombinant factor VIII normalized the rate of TAT generation. Thus, coagulation in hemophilia A blood at 25 pmol/L TF is impaired, with significantly slower thrombin generation than normal during the propagation phase; this reduced thrombin appears to affect FPA production and factor V activation more profoundly than platelet activation. At the same level of TF in factor XI-deficient blood (XI:C <2%), only minor differences in clotting or product formation (FPA, osteonectin, and factor Va) were observed. Using reduced levels of initiator (5 pmol/L TF), the reaction was more strongly influenced by factor XI deficiency. Clot formation was delayed from 11.1 to 15.7 minutes, which shortened to 9.7 minutes with factor XI replacement. The maximum thrombin generation rate observed ( approximately 37 nmol TAT/L/min) was approximately one third that for normal (110 nmol/L TAT/min) or with factor XI replacement (119 nmol TAT/L/min). FPA release, factor V activation, and release of platelet osteonectin were slower in factor XI-deficient blood than in normal blood. The data demonstrate that factor XI deficiency results in significantly delayed clot formation only at sufficiently low TF concentrations. However, even at these low TF concentrations, significant thrombin is generated in the propagation phase after formation of the initial clot in hemophilia C blood.
在接触途径被抑制的情况下，比较了来自正常、因子VIII缺乏和因子XI缺乏供体的人血液中组织因子（TF）诱导的凝血情况。通过免疫测定和免疫印迹法对淬灭样品中的纤维蛋白肽A（FPA）、凝血酶 - 抗凝血酶（TAT）、因子V活化和骨连接蛋白进行分析，以研究反应进程。在用25 pmol/L TF处理的甲型血友病血液（因子VIII：C <1%）中，与正常血液相比，凝血显著延迟，而用重组因子VIII（1 U/mL）替代后，凝血时间恢复至接近正常值。在实验过程中，FPA释放比正常血液或补充了因子VIII的血友病血液慢，但在实验结束时观察到有明显释放。因子V活化明显受损，重链和轻链的出现均比正常或替代情况慢。正常血液和因子VIII缺乏血液之间的血小板活化（骨连接蛋白释放）差异较小，两者曲线的中点相差在1分钟以内。在凝血后传播阶段的凝血酶生成在因子VIII缺乏时严重受损，降至正常血液中速率（55 nmol TAT/L/min）的不到1/29（<1.9 nmol TAT/L/min）。用重组因子VIII替代可使TAT生成速率恢复正常。因此，在25 pmol/L TF时，甲型血友病血液中的凝血受损，在传播阶段凝血酶生成明显比正常情况慢；这种凝血酶生成减少似乎对FPA产生和因子V活化的影响比对血小板活化的影响更显著。在因子XI缺乏血液（XI：C <2%）中，在相同TF水平下，仅观察到凝血或产物形成（FPA、骨连接蛋白和因子Va）有微小差异。使用较低水平的启动剂（5 pmol/L TF）时，反应受因子XI缺乏的影响更大。凝血形成从11.1分钟延迟至15.7分钟，补充因子XI后缩短至9.7分钟。观察到的最大凝血酶生成速率（约37 nmol TAT/L/min）约为正常情况（110 nmol/L TAT/min）或补充因子XI后（119 nmol TAT/L/min）的三分之一。因子XI缺乏血液中FPA释放、因子V活化和血小板骨连接蛋白释放均比正常血液慢。数据表明，仅在足够低的TF浓度下，因子XI缺乏才会导致凝血形成显著延迟。然而，即使在这些低TF浓度下，丙型血友病血液在初始凝块形成后的传播阶段仍会产生大量凝血酶。
