Independent modulation of von Willebrand factor and fibrinogen binding to the platelet membrane glycoprotein IIb/IIIa complex as demonstrated by monoclonal antibody.
Independent modulation of von Willebrand factor and fibrinogen binding to the platelet membrane glycoprotein IIb/IIIa complex as demonstrated by monoclonal antibody.
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单克隆抗体证明了血管性血友病因子和纤维蛋白原与血小板膜糖蛋白 IIb/IIIa 复合物结合的独立调节。
DOI：
10.1172/jci112193
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发表时间：
1985
期刊：
影响因子：
--
通讯作者：
Ruggeri,ZM
中科院分区：
文献类型：
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作者：
Lombardo,VT;Hodson,E;Roberts,JR;Kunicki,TJ;Zimmerman,TS;Ruggeri,ZM
在这项研究中，我们使用了两个新的单抗，命名为LJP5和LJP9，以及先前描述的一个，AP2，都是针对血小板膜糖蛋白(GP)IIb/IIIa复合体的。它们均不能与游离的GPIIb或GPIIa发生反应。LJP5和LJP9的单价Fab片段以饱和方式与未刺激的血小板结合，但在37℃不加细胞外钙的情况下，结合显著降低。LJP9的结合不受AP2的影响，但可被过量的LJP5阻断。相反，在AP2和LJP9存在下，LJP5的结合被阻断。因此，这些抗体与不同的GPIIb/IIIa表位结合。在饱和状态下，LJP5与未刺激的血小板结合在2.41~10.9×10(4)分子/血小板之间，LJP9在3.47~9.1×10(4)分子/血小板之间(分别进行11次和10次实验)。凝血酶刺激后，结合力增加了50%。LJP5和LJP9的缔合常数Ka分别为2.7×10(7)M-1和3.85×10(7)M-1。LJP5和LJP9均部分抑制45Ca~(2+)与未刺激的血小板表面的结合。此外，两种抗体都阻断了von Willebrand因子(VWF)与刺激的血小板的结合，而只有LJP9，而不是LJP5，阻止了纤维蛋白原的结合。LJP9也是一种有效的血小板聚集抑制物，而LJP5在这方面没有作用。本研究的结果表明，针对不同的GPIIb/IIIA表位的单抗可以独立地调节vWF和纤维蛋白原与刺激的血小板的结合。
In this study we have used two new monoclonal antibodies, designated LJP5 and LJP9, as well as a previously described one, AP2, all specific for the platelet membrane glycoprotein (GP)IIb/IIIa complex. None of them reacted with dissociated GPIIb or GPIIIa. The monovalent Fab fragment of both LJP5 and LJP9 bound to unstimulated platelets in a saturable manner, but binding was markedly decreased after platelets had been incubated at 37 degrees C in the absence of added extracellular calcium. The binding of LJP9 was not affected by AP2, but was blocked by excess LJP5. On the contrary, the binding of LJP5 was blocked in the presence of both AP2 and LJP9. Thus, these antibodies bound to distinct epitopes of GPIIb/IIIa. At saturation, the binding to unstimulated platelets was between 2.41 and 10.9 X 10(4) molecules/platelet for LJP5 and between 3.47 and 9.1 X 10(4) molecules/platelet for LJP9 (range of 11 and 10 experiments, respectively). Binding increased up to 50% after thrombin stimulation. The estimated association constant, Ka, was 2.7 X 10(7) M-1 for LJP5 and 3.85 X 10(7) M-1 for LJP9. Both LJP5 and LJP9 partially inhibited the association of 45Ca2+ with the surface of unstimulated platelets. Moreover, both antibodies blocked the binding of von Willebrand factor (vWF) to stimulated platelets, whereas only LJP9, but not LJP5, blocked fibrinogen binding. LJP9 was also a potent inhibitor of platelet aggregation, whereas LJP5 was without effect in this regard. The results of the present study demonstrate that independent modulation of vWF and fibrinogen binding to stimulated platelets can be attained with monoclonal antibodies directed against distinct epitopes of GPIIb/IIIa.Images