Parker R I, Gralnick H R
Blood. 1986 Sep;68(3):732-6.
We studied the effects(s) of two monoclonal antibodies, 6D1 and 10E5 (directed against platelet glycoprotein Ib [GPIb] and the GPIIb/IIIa complex, respectively), and purified human plasma fibrinogen on the binding of released platelet-von Willebrand factor (vWf) to the platelet surface. Neither of the monoclonal antibodies nor fibrinogen had any effect on the amount of platelet-vWf expressed on unstimulated platelets or on the amount expressed on platelets stimulated in the absence of extracellular Ca++. However, the antibody directed against GPIIb/IIIa inhibited 72% of the thrombin-induced increase in the platelet-vWf bound to the platelet surface when platelets were stimulated in the presence of 5 mmol/L Ca++. The antibody against GPIb did not inhibit the surface expression of platelet-vWf on stimulated platelets in the presence of Ca++. Purified normal human fibrinogen inhibited the surface binding of platelet-vWf to thrombin-stimulated platelets to a degree similar to that observed with the monoclonal antibody directed against the GPIIb/IIIa complex. These data indicate that platelet-vWf released from platelets binds primarily to the GPIIb/IIIa complex at or near the plasma fibrinogen binding site.
我们研究了两种单克隆抗体6D1和10E5（分别针对血小板糖蛋白Ib [GPIb]和GPIIb/IIIa复合物）以及纯化的人血浆纤维蛋白原对释放的血小板血管性血友病因子（vWf）与血小板表面结合的影响。这两种单克隆抗体和纤维蛋白原对未刺激血小板上表达的血小板vWf量或在无细胞外Ca++刺激的血小板上表达的量均无任何影响。然而，当血小板在5 mmol/L Ca++存在下受到刺激时，针对GPIIb/IIIa的抗体抑制了72%的凝血酶诱导的与血小板表面结合的血小板vWf增加。在Ca++存在下，针对GPIb的抗体并未抑制刺激血小板上血小板vWf的表面表达。纯化的正常人纤维蛋白原抑制血小板vWf与凝血酶刺激血小板的表面结合，其程度与针对GPIIb/IIIa复合物的单克隆抗体所观察到的相似。这些数据表明，从血小板释放的血小板vWf主要在血浆纤维蛋白原结合位点处或其附近与GPIIb/IIIa复合物结合。
