Bauer K A, Kass B L, ten Cate H, Bednarek M A, Hawiger J J, Rosenberg R D
Charles A. Dana Research Institute, Beth Israel Hospital, Boston, MA 02215.
Blood. 1989 Nov 1;74(6):2007-15.
A sensitive radioimmunoassay (RIA) for the fragment that is liberated from factor X when this zymogen is activated by factor VII/VIIa-tissue factor or factor IXa was developed. Antisera were raised in rabbits to a synthetic 15 amino acid peptide containing the COOH-terminal sequence of the activation fragment coupled to bovine serum albumin with glutaraldehyde. The reactivity of the antibody population obtained toward the factor X zymogen was negligible (less than 1/36,000 that of the activation peptide on a molar basis). However, because other plasma constituents contributed to a nonspecific basal signal in the RIA, a procedure by which the peptide could be reproducibly extracted from plasma was developed. The mean level of this species in normal individuals younger than the age of 40 was 66.4 pmol/L, and elevations up to 550 pmol/L were observed in patients with evidence of disseminated intravascular coagulation. The validity of these measurements of factor X activation is supported by the fact that the RIA signal migrates on reverse-phase high pressure liquid chromatography in a manner identical to that of the native peptide and can be quantitatively recovered. The mean concentration of the activation fragment was markedly decreased to 25.7 pmol/L in patients with hereditary factor VII deficiency (P = .0001 v normal controls), whereas the mean level in subjects with factor VIII deficiency was 61.1 pmol/L (P greater than .1 v normal controls). These data indicate that the basal (ie, in the absence of thrombosis or provocative stimuli) levels of FXP under in vivo conditions result mainly from the activity of the extrinsic pathway.
开发了一种灵敏的放射免疫测定法（RIA），用于检测当凝血因子X被凝血因子VII/VIIa-组织因子或凝血因子IXa激活时释放的片段。用含有激活片段COOH末端序列的15个氨基酸合成肽与牛血清白蛋白通过戊二醛偶联，在兔体内制备抗血清。所获得的抗体群体对凝血因子X酶原的反应性可忽略不计（摩尔基础上小于激活肽的1/36,000）。然而，由于其他血浆成分在RIA中产生非特异性基础信号，因此开发了一种可从血浆中可重复提取该肽的方法。40岁以下正常个体中该物质的平均水平为66.4 pmol/L，在有弥散性血管内凝血证据的患者中观察到高达550 pmol/L的升高。凝血因子X激活这些测量值的有效性得到以下事实的支持：RIA信号在反相高压液相色谱上的迁移方式与天然肽相同，并且可以定量回收。遗传性凝血因子VII缺乏症患者中激活片段的平均浓度显著降低至25.7 pmol/L（与正常对照组相比，P = .0001），而凝血因子VIII缺乏症患者中的平均水平为61. pmol/L（与正常对照组相比，P大于.1）。这些数据表明，体内条件下FXP的基础（即无血栓形成或激发刺激）水平主要源于外源性途径的活性。
