Eisenberg P R, Jaffe A S, Stump D C, Collen D, Bovill E G
Cardiovascular Division, Washington University School of Medicine, St. Louis, Missouri 63110.
Circulation. 1990 Oct;82(4):1159-68. doi: 10.1161/01.cir.82.4.1159.
Concentrations of cross-linked fibrin degradation products (XL-FDPs) in plasma, measured by enzyme-linked immunosorbent assays (ELISAs) based on monoclonal antibodies (MAbs) raised against fragment D-dimer of cross-linked fibrin, increase when patients are given fibrinolytic agents. Whether XL-FDPs derive from circulating cross-linked fibrin polymers in plasma, compared with clot-associated fibrin, has been questioned because increases in XL-FDP are measured by some assays after fibrinolysis in vitro in the absence of clot. We characterized the source of XL-FDP immunoreactivity in plasma of patients with acute myocardial infarction and ischemic heart disease and the response to plasminogen activation in vitro induced by pharmacological concentrations of tissue-type plasminogen activator (t-PA) and streptokinase. XL-FDPs were measured with two different ELISA. One, "pan-specific tag ELISA," was based on a capture MAb specific for XL-FDP and a tag MAb that recognizes an epitope exposed in the fragment D region of both fibrin and fibrinogen, whereas the other, "fibrin-specific tag ELISA," was based on a capture and tag MAbs both specific for fibrin. After plasminogen activation was induced in vitro in plasma from patients with myocardial infarction, increased concentrations of XL-FDP were measured by the pan-specific tag ELISA; however, concentrations measured with the fibrin-specific tag ELISA were not increased. To determine the mechanism for this discrepancy, plasma was subjected to immunoadsorption with a MAb specific for fragment D-dimer before and after in vitro activation of the fibrinolytic system and immunoblotting with a fragment D-dimer-specific MAb and with the pan-specific MAb. Increased concentrations of fragment D-dimer, as well as fibrinogen fragment D at high concentrations, were recognized by the specific MAb. Non-cross-linked fragments were also shown by immunoblotting with the pan-specific MAb to coprecipitate with cross-linked fibrin fragments. This suggested the increased concentrations of XL-FDP measured by the pan-specific tag ELISA after in vitro activation of the fibrinolytic system were due to detection of non-cross-linked fibrinogen fragments. However, fibrin fragment D-dimer concentrations were found to increase in plasma of 15 patients given t-PA for acute myocardial infarction. We conclude fragment D-dimer in plasma of patients during thrombolysis does not originate from circulating soluble cross-linked fibrin but rather is a marker of solid-phase fibrin dissolution, which may be quantitated with assays based on capture and tag antibodies that do not detect fibrinogen or its degradation products.
通过基于针对交联纤维蛋白D - 二聚体片段产生的单克隆抗体（MAb）的酶联免疫吸附测定（ELISA）测量，血浆中交联纤维蛋白降解产物（XL - FDPs）的浓度在患者接受纤溶药物时会升高。与凝块相关纤维蛋白相比，XL - FDPs是否源自血浆中循环的交联纤维蛋白聚合物一直受到质疑，因为在体外无凝块的纤溶后，一些测定法可测得XL - FDP升高。我们对急性心肌梗死和缺血性心脏病患者血浆中XL - FDP免疫反应性的来源以及药理浓度的组织型纤溶酶原激活剂（t - PA）和链激酶在体外诱导的纤溶酶原激活反应进行了表征。用两种不同的ELISA测定XL - FDPs。一种是“泛特异性标记ELISA”，基于对XL - FDP特异的捕获MAb和识别纤维蛋白和纤维蛋白原D区暴露表位的标记MAb；另一种是“纤维蛋白特异性标记ELISA”，基于对纤维蛋白特异的捕获和标记MAb。在心肌梗死患者血浆中体外诱导纤溶酶原激活后，用泛特异性标记ELISA测得XL - FDP浓度升高；然而，用纤维蛋白特异性标记ELISA测得的浓度并未升高。为确定这种差异的机制，在体外激活纤溶系统前后，用针对D - 二聚体片段的MAb对血浆进行免疫吸附，并用D - 二聚体特异性MAb和泛特异性MAb进行免疫印迹。特异性MAb识别出D - 二聚体片段浓度升高以及高浓度的纤维蛋白原片段D。用泛特异性MAb进行免疫印迹也显示非交联片段与交联纤维蛋白片段共沉淀。这表明纤溶系统体外激活后用泛特异性标记ELISA测得的XL - FDP浓度升高是由于检测到非交联纤维蛋白原片段。然而，在15例接受t - PA治疗急性心肌梗死的患者血浆中发现纤维蛋白片段D - 二聚体浓度升高。我们得出结论，溶栓期间患者血浆中的D - 二聚体并非源自循环可溶性交联纤维蛋白，而是固相纤维蛋白溶解的标志物，可用基于不检测纤维蛋白原或其降解产物的捕获和标记抗体的测定法进行定量。
