Different Anticoagulant and Immunological Properties of Anti-Prothrombin Antibodies in Patients with Antiphospholipid Antibodies
Different Anticoagulant and Immunological Properties of Anti-Prothrombin Antibodies in Patients with Antiphospholipid Antibodies
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DOI：
10.1055/s-0038-1655994
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发表时间：
1997-03
影响因子：
6.7
通讯作者：
M. Galli;G. Beretta;M. Daldossi;E. Bevers;T. Barbui
中科院分区：
文献类型：
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作者：
M. Galli;G. Beretta;M. Daldossi;E. Bevers;T. Barbui
狼疮抗凝剂（LA）抗体是获得性凝血抑制剂，与抗心磷脂（aCL）抗体一起属于抗磷脂抗体家族。由于LA抗体通过识别脂质结合的凝血酶原复合物来影响凝血反应，因此它们可以更好地命名为抗凝血酶原抗体。我们研究了他们的免疫学特性，在血浆中的59例患者的抗磷脂抗体通过特定的ELISA系统，允许这些抗体与人凝血酶原和阴离子磷脂的相互作用的表征。凝血酶原的呈现模式被发现极大地影响抗凝血酶原抗体的反应性。事实上，当用普通聚苯乙烯板来固定凝血酶原时，几乎没有观察到结合。相反，当凝血酶原包被在高活化PVC ELISA板上时，34个样品（58%）含有识别固相中人凝血酶原的抗体。特别是，IgG抗体被发现在21血浆和IgM在22; IgG和IgM同种型都存在于9这些情况下。在检测针对磷脂酰丝氨酸（PS）结合凝血酶原的钙介导复合物的抗体的ELISA中观察到更高的流行率：53个样品（90%），用心磷脂脂质体预吸附以去除aCL抗体，显示存在IgG和/或IgM抗凝血酶原抗体。当根据免疫球蛋白同种型分析结果时，分别发现44（75%）和39（66%）个样本含有IgG和IgM抗凝血酶原抗体。30例患者血浆中同时存在IgG和IgM。这些样品中只有一半也与PVC结合的凝血酶原反应。显然，用于检测PS结合凝血酶原复合物的抗体的ELISA的较高阳性率不是由于两种系统中可用抗原量的差异，如通过用兔多克隆抗人凝血酶原抗血清进行的结合实验所判断的。最后，通过稀释的罗素蝰蛇毒液时间和稀释的活化部分凝血活酶时间评价了14种总IgG制剂的抗凝特性（其中12种制剂在两种ELISA系统中都含有阳性的抗凝血酶原抗体，而另外2种情况仅与PVC结合的凝血酶原或仅与PS结合的凝血酶原反应）。为了排除制剂中所含aCL抗体的β2-糖蛋白I（β2-GPI）依赖性抗凝作用，在β2-GPI缺乏血浆中进行凝血试验。6种制剂在两种试验系统中均未显示抗凝活性，表明存在2种类型的IgG抗凝血酶原抗体，其抗凝特性不同。这些结果表明，抗凝血酶原抗体类似于ACL抗体在“体外”凝血反应的行为，并强调了广泛的异质性抗磷脂抗体。
Summary Lupus anticoagulant (LA) antibodies are acquired inhibitors of coagulation belonging – together with anticardiolipin (aCL) antibodies – to the family of antiphospholipid antibodies. Since LA antibodies affect coagulation reactions via recognition of the complex of lipid-bound prothrombin, they may be better named anti-prothrombin antibodies. We studied their immunological properties in the plasma of 59 patients with antiphospholipid antibodies by means of specific ELISA systems that allowed the characterization of the interaction of these antibodies with human prothrombin and anionic phospholipids. The mode of presentation of prothrombin was found to greatly influence the reactivity of anti-prothrombin antibodies. In fact, when plain polystyrene plates were used to immobilize prothrombin, virtually no binding was observed. Conversely, when prothrombin was coated on high-activated PVC ELISA plates, 34 samples (58%) contained antibodies that recognize human prothrombin in solid phase. In particular, IgG antibodies were found in 21 plasmas and IgM in 22; both IgG and IgM isotypes were present in 9 of these cases. A higher prevalence was observed in the ELISA for the detection of the antibodies directed at the calcium- mediated complex of phosphatidylserine (PS)-bound prothrombin: 53 samples (90%), preadsorbed with cardiolipin liposomes to remove aCL antibodies, showed the presence of IgG and/or IgM anti-prothrombin antibodies. When the results were analyzed according to the immunoglobulin isotypes, 44 (75%) and 39 (66%) samples were found to contain IgG and IgM anti-prothrombin antibodies, respectively. Both IgG and IgM were present in the plasma of 30 patients. Only half of these samples reacted also with PVC-bound prothrombin. Apparently, the higher rate of positivity of the ELISA for the detection of antibodies to the complex of PS-bound prothrombin was not due to differences in the amount of antigen available in the 2 systems, as judged by binding experiments performed with a rabbit polyclonal anti-human prothrombin antiserum. Finally, the anticoagulant properties of 14 total IgG preparations (12 of them contained anti-prothrombin antibodies positive in both ELISA systems, whereas the other 2 cases reacted either with PVC-bound prothrombin only or with PS-bound prothrombin only) were evaluated by diluted Russell’s Viper Venom Time and by diluted activated Partial Thromboplastin Time. To rule out the β2-glycoprotein I (β2-GPI)-de- pendent anticoagulant effect of the aCL antibodies contained in the preparations, the coagulation tests were performed in (β2-GPI deficient plasma. Six preparations failed to show anticoagulant activity in both assay systems, suggesting that 2 types of IgG anti-prothrombin antibodies exist, that differ with respect to their anticoagulant properties. These findings suggest that anti-prothrombin antibodies resemble aCL antibodies with respect to the behaviour in “in vitro” coagulation reactions and underline the wide heterogeneity of antiphospholipid antibodies.