Leistikow E A, Barnhart M I, Escolar G, White J G
Department of Pediatrics, Wayne State University School of Medicine, Detroit, Michigan.
Br J Haematol. 1990 Jan;74(1):93-100. doi: 10.1111/j.1365-2141.1990.tb02544.x.
Human platelets were incubated with gold particles coupled to fibrinogen to label the glycoprotein IIb-IIIa (GPIIb-IIIa) receptor after initial activation of the cells by contact with formvar-coated grid and glass surfaces. Fibrinogen-gold (Fgn-Au) markers were absent on discoid platelets, but diffusely spread over the surface and extended pseudopods of early dendritic cells. Conversion to spread platelets resulted in movement of ligand-receptor complexes away from the cell margin toward cell centres. However, Fgn-Au gold did not concentrate in the central region. Rather, the Fgn-Au, GPIIb-IIIa complexes in the middle of spread platelets appeared to move toward a belt-like, intermediate zone, as did the ligand receptor complexes from the cell margin and pseudopods. The ultimate destination of the mobile receptor-ligand complexes, however, appeared to be channels of the surface-connected open canalicular system (OCS). Fgn-Au was concentrated in OCS channels of most dendritic and a small proportion of spread platelets. The decreased frequency of Fgn-Au filled channels in more transformed platelets may have been due to collapse or evagination of the OCS. Examination of platelets exposed to Fgn-Au after spreading on glass and then prepared for thin sections confirmed that the OCS was the final destination for mobile ligand receptor complexes on surface-activated platelets. Findings of this study are consistent with previous work showing clearance of mobile receptor-ligand complexes to the OCS of platelets activated in suspension.
人血小板在与福尔马林包被的网格和玻璃表面接触初始激活细胞后，与偶联纤维蛋白原的金颗粒一起孵育，以标记糖蛋白IIb-IIIa（GPIIb-IIIa）受体。盘状血小板上没有纤维蛋白原-金（Fgn-Au）标记物，但在早期树突状细胞的表面呈弥漫性分布并延伸出伪足。转化为伸展型血小板导致配体-受体复合物从细胞边缘向细胞中心移动。然而，Fgn-Au并未集中在中央区域。相反，伸展型血小板中部的Fgn-Au、GPIIb-IIIa复合物似乎朝着带状的中间区域移动，来自细胞边缘和伪足的配体受体复合物也是如此。然而，移动的受体-配体复合物的最终目的地似乎是表面连接的开放小管系统（OCS）的通道。Fgn-Au集中在大多数树突状和一小部分伸展型血小板的OCS通道中。在更多转化型血小板中，Fgn-Au填充通道的频率降低可能是由于OCS的塌陷或外翻。对在玻璃上伸展后暴露于Fgn-Au然后制备薄切片的血小板进行检查证实，OCS是表面激活血小板上移动配体受体复合物的最终目的地。本研究结果与先前的工作一致，先前工作表明悬浮激活的血小板的移动受体-配体复合物会清除到OCS中。
