Patients with congenital factor V deficiency have decreased factor Xa binding sites on their platelets.
Patients with congenital factor V deficiency have decreased factor Xa binding sites on their platelets.
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先天性 V 因子缺乏症患者血小板上的 Xa 因子结合位点减少。
DOI：
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发表时间：
1978
影响因子：
15.9
通讯作者：
P. Majerus
中科院分区：
文献类型：
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作者：
J. Miletich;D. Majerus;P. Majerus
人血小板具有血浆凝固因子 X(a) 的结合位点，该结合位点仅在血小板释放反应后可用。来自 15 名正常供体的血小板每个血小板结合 216+/-52 (SD) 个因子 X(a) 分子。因子 X(a) 与其血小板表面受体的结合导致因子 X(a) 从凝血酶原形成凝血酶的催化活性增加 300,000 倍。在使用来自 15 名正常供体的血小板进行的实验中，血小板结合因子 X(a) 的周转数为每分钟每摩尔因子 X(a) 1,850+/-460 mol 凝血酶/ml。研究人员对五名不同程度缺乏因子 V 的患者的血小板进行了研究，以确定凝血因子 V 是否参与因子 X(a)-血小板相互作用的任一方面。在每种情况下，因子X(a)与血小板的结合以及伴随的凝血酶形成速率的增加要么同时减少，要么不存在，其值范围为对照值的0至45%。当检测到血小板结合时，因子 V 缺乏患者的因子 X(a) 的表观亲和力正常。经过凝血酶处理的对照血小板的上清液含有因子 V 活性，纠正了三名测试患者血小板的因子 X(a) 结合缺陷。用同源抗体测定的免疫反应性因子 V 与来自一名因子 V 缺乏患者的血小板功能性因子 V 活性相对应，表明该患者的血小板中正常因子 V 的量减少。来自患者的血小板结合因子 X(a) 和增加凝血酶形成速率的能力与每个患者出血性疾病的严重程度相关性优于因子 V 的血浆水平。结果表明，因子 V 是因子 X(a)-血小板相互作用所必需的，并且血小板表面凝血酶的形成对于正常止血很重要。
Human platelets have binding sites for plasma coagulation Factor X(a) that are available only after the platelet release reaction. Platelets from 15 normal donors bound 216+/-52 (SD) molecules of Factor X(a) per platelet. The association of Factor X(a) with its platelet surface receptor results in a 300,000-fold increase in the catalytic activity of Factor X(a) in forming thrombin from prothrombin. The turnover number for platelet-bound Factor X(a) was 1,850+/-460 mol thrombin/ml per min per mol Factor X(a) in experiments with platelets from 15 normal donors. Platelets from five patients with varying degrees of Factor V deficiency were investigated to determine whether or not coagulation Factor V participates in either aspect of the Factor X(a)-platelet interaction. The binding of Factor X(a) to platelets and the accompanying increase in rate of thrombin formation were either reduced in parallel or absent in each case with values ranging from 0 to 45% of control values. The apparent affinity of Factor X(a) from Factor V-deficient patients was normal when platelet binding was detected. The supernate from thrombin-treated control platelets, which contains Factor V activity, corrected the Factor X(a) binding deficiency of the platelets from three patients tested. Immunoreactive Factor V determined with an homologous antibody corresponded to the functional Factor V activity of platelets from one patient with Factor V deficiency, suggesting that the patient's platelets have a decreased amount of normal Factor V. The ability of platelets from the patients to bind Factor X(a) and increase the rate of thrombin formation correlated with the severity of each patient's bleeding disorder better than the plasma level of Factor V. The results indicate that Factor V is required for the Factor X(a)-platelet interaction and that thrombin formation at the platelet surface is important in normal hemostasis.