McKeown L, Vail M, Williams S, Kramer W, Hansmann K, Gralnick H
Hematology Service, National Institutes of Health, Bethesda, MD 20892.
Blood. 1994 May 15;83(10):2866-71.
The Naka isoantigen is expressed on glycoprotein (GP) IV (CD36), a platelet membrane GP that has been identified as having a role in platelet interactions with collagen and thrombospondin and in binding Plasmodium falciparum-infected erythrocytes to endothelial cells and melanoma cells. We have studied normal platelets and Naka- platelets from two Japanese donors that have 1% of GPIV by concentration-dependent antibody binding and flow cytometry. We studied the adherence of normal and Naka- platelets to types I, III, and IV collagen in static and to type I collagen in flowing systems at high shear force. We have also studied aggregation of normal and Naka- platelets to type I collagen. Naka- platelets showed normal or increased aggregation to type I collagen and normal adhesion to types I, III, and IV collagen in the presence of Mg++ or EDTA. Platelet aggregation and adhesion were inhibited by the anti-alpha 2 beta 1 antibody 176D7 to the same extent in Naka- as in normal platelets. We also studied endogenous thrombospondin surface expression and found that thrombin-stimulated Naka- platelets expressed the same amount of thrombospondin as did normal platelets. From our studies with Naka- platelets, we cannot identify a definitive role for GPIV in platelet aggregation, in adhesion to types I, III, and IV collagen, or in endogenous thrombospondin binding to platelets.
中抗原在糖蛋白（GP）IV（CD36）上表达，GPIV是一种血小板膜糖蛋白，已被确定在血小板与胶原蛋白和血小板反应蛋白的相互作用中，以及在恶性疟原虫感染的红细胞与内皮细胞和黑色素瘤细胞的结合中发挥作用。我们通过浓度依赖性抗体结合和流式细胞术研究了来自两名日本供体的正常血小板和中抗原阴性血小板，其GPIV含量为1%。我们研究了正常血小板和中抗原阴性血小板在静态条件下对I型、III型和IV型胶原蛋白的黏附，以及在高剪切力流动系统中对I型胶原蛋白的黏附。我们还研究了正常血小板和中抗原阴性血小板对I型胶原蛋白的聚集情况。在存在镁离子或乙二胺四乙酸（EDTA）的情况下，中抗原阴性血小板对I型胶原蛋白的聚集正常或增加，对I型、III型和IV型胶原蛋白的黏附正常。抗α2β1抗体176D7对中抗原阴性血小板和正常血小板的血小板聚集和黏附的抑制程度相同。我们还研究了内源性血小板反应蛋白的表面表达，发现凝血酶刺激的中抗原阴性血小板表达的血小板反应蛋白量与正常血小板相同。通过对中抗原阴性血小板的研究，我们无法确定GPIV在血小板聚集、对I型、III型和IV型胶原蛋白的黏附或内源性血小板反应蛋白与血小板的结合中的确切作用。
