George J N, Thoi L L, McManus L M, Reimann T A
Blood. 1982 Oct;60(4):834-40.
Methods have been developed to isolate human platelet membrane fragments from plasma and serum. Rabbit antibody produced against the human platelet membrane glycoprotein complex, IIb/IIIa, was utilized in an immunoelectrophoretic assay to evaluate the amount of this antigen in various microparticle preparations. The serum concentration of platelet microparticles was more than tenfold greater than that observed for plasma (65 micrograms/ml versus 4.4 micrograms/ml, respectively). Ultrastructural evaluation of either plasma or serum-derived microparticles disclosed a variety of membrane fragments and membrane-bound vesicles with occasional fragments of red blood cells, white blood cells, and platelets. In contrast, microparticle preparations derived from isolated washed platelets after thrombin stimulation contained a heterogeneous array of membrane fragments, vesicles, and granules but no identifiable red cell, white cell, or platelet fragments. Thus, these studies demonstrate that normal human plasma and serum contain platelet membrane fragments that are produced during cell activation. If a similar loss of platelet membranes occurs in vivo following reversible platelet activation, it is possible that the resulting membrane modifications may be of importance in both the structural and functional changes that develop during platelet senescence.
已开发出从血浆和血清中分离人血小板膜片段的方法。利用针对人血小板膜糖蛋白复合物IIb/IIIa产生的兔抗体，通过免疫电泳分析来评估各种微粒制剂中该抗原的含量。血小板微粒的血清浓度比血浆中观察到的浓度高十多倍（分别为65微克/毫升和4.4微克/毫升）。对血浆或血清来源的微粒进行超微结构评估发现了各种膜片段和膜结合囊泡，偶尔还有红细胞、白细胞和血小板的片段。相比之下，凝血酶刺激后从分离的洗涤血小板中获得的微粒制剂包含一系列异质的膜片段、囊泡和颗粒，但没有可识别的红细胞、白细胞或血小板片段。因此，这些研究表明正常人血浆和血清中含有细胞激活过程中产生的血小板膜片段。如果在体内可逆性血小板激活后发生类似的血小板膜丢失，那么由此产生的膜修饰可能在血小板衰老过程中发生的结构和功能变化中都具有重要意义。
