Vallar L, Regnault V, Latger-Cannard V, Lecompte T
Laboratoire Franco-Luxembourgeois de Recherche Biomédicale (CNRS and CRP-Santé), Center Universitaire, Luxembourg.
Thromb Haemost. 2001 Feb;85(2):314-9.
We have investigated beta2-glycoprotein I (beta2GPI) binding to platelet-derived microparticles (PMP) and its effect on GPIIb/IIIa. PMP were isolated from washed human platelets after stimulation with A23187, and analyzed by surface plasmon resonance spectroscopy. Beta2GPI as well as activated protein C (APC) or annexin V bound to PMP-coated sensorchips, demonstrating exposure of anionic phospholipids on immobilized PMP. Beta2GPI binding was impaired by calcium and occurred in a concentration-dependent manner with apparent k(on) = 2.6 x 10(4) M(-1) s(-1) and k(off) = 4.4 x 10(-3) s(-1), corresponding to a KD value of 1.7 x 10(-7) M. When analyzed by flow cytometry, the binding of certain mAbs specific for GPIIb and/or GPIIIa was reduced in the presence of beta2GPI but not of APC or annexin V, whereas the binding of anti-GPIb or anti-P-selectin mAbs, or of soluble fibrinogen remained unchanged. These results suggest a broad but specific influence of beta2GPI on GPIIb/IIIa immunoreactivity, and indicate that beta2GPI may act as a modulator of GPIIb/IIIa-dependent functions of PMP.
我们研究了β2-糖蛋白I（β2GPI）与血小板衍生微粒（PMP）的结合及其对GPIIb/IIIa的影响。用A23187刺激后，从洗涤过的人血小板中分离出PMP，并通过表面等离子体共振光谱进行分析。β2GPI以及活化蛋白C（APC）或膜联蛋白V与包被有PMP的传感芯片结合，表明固定化PMP上有阴离子磷脂暴露。β2GPI的结合受钙抑制，并以浓度依赖方式发生，表观结合速率常数k(on)=2.6×10⁴ M⁻¹ s⁻¹，解离速率常数k(off)=4.4×10⁻³ s⁻¹，对应解离常数KD值为1.7×10⁻⁷ M。通过流式细胞术分析时，在存在β2GPI的情况下，某些对GPIIb和/或GPIIIa特异的单克隆抗体（mAb）的结合减少，但APC或膜联蛋白V存在时则不然，而抗GPIb或抗P-选择素mAb或可溶性纤维蛋白原的结合保持不变。这些结果表明β2GPI对GPIIb/IIIa免疫反应性有广泛但特异的影响，并表明β2GPI可能作为PMP的GPIIb/IIIa依赖性功能的调节剂。
