Cramer E M, Vainchenker W, Vinci G, Guichard J, Breton-Gorius J
Blood. 1985 Dec;66(6):1309-16.
An immunogold method was used for investigating the subcellular localization of von Willebrand factor (vWF) and fibrinogen (Fg) in platelets and cultured megakaryocytes from normal subjects and from three patients with the gray platelet syndrome (GPS), a rare congenital disorder characterized by the absence of alpha-granules. In normal platelets at rest, vWF was detected exclusively in alpha-granules, with a characteristic distribution: gold particles were localized at one pole of each labeled granule, outlining the inner face of its membrane. vWF was distributed similarly in the alpha-granules of megakaryocytes at day 12 of culture, where it was also found in small vesicles near the Golgi complex. In contrast, Fg was observed in the whole matrix of all platelet alpha-granules but not in the nucleoids. In platelets from three patients with GPS, vWF and Fg were distributed homogeneously in the rare normal alpha-granules, which could be recognized by their size, and also in small granules identified as abnormal alpha-granules, which were similar in size to the small, possibly immature granules present in normal megakaryocytes. In addition, in some unstimulated platelets, Fg labeling was associated with dense material in the lumen of the surface-connected canalicular system (SCCS). At day 12 of culture, megakaryocytes from the patients with GPS contained some small alpha-granules labeled for Fg and vWF identical to those found in mature platelets. The majority of alpha-granules of normal size appeared partially or completely empty. Thus, we conclude that vWF is distributed differently from Fg in normal alpha-granules, and that unstimulated platelets from patients with GPS contain Fg and vWF in a population of small granules identifiable as abnormal alpha-granules only by immunoelectron microscopy. In addition, the presence of Fg in the SCCS of gray platelets suggests a spontaneous release of the alpha-granule content.
采用免疫金法研究正常受试者以及三名灰色血小板综合征（GPS）患者（一种以缺乏α-颗粒为特征的罕见先天性疾病）的血小板和培养的巨核细胞中血管性血友病因子（vWF）和纤维蛋白原（Fg）的亚细胞定位。在静息的正常血小板中，vWF仅在α-颗粒中被检测到，具有特征性分布：金颗粒位于每个标记颗粒的一极，勾勒出其膜的内表面。在培养第12天的巨核细胞α-颗粒中，vWF的分布类似，在高尔基体附近的小泡中也有发现。相比之下，Fg在所有血小板α-颗粒的整个基质中均有观察到，但在核仁中未发现。在三名GPS患者的血小板中，vWF和Fg均匀分布于罕见的正常α-颗粒（可通过其大小识别）以及被鉴定为异常α-颗粒的小颗粒中，这些异常α-颗粒的大小与正常巨核细胞中存在的可能未成熟的小颗粒相似。此外，在一些未受刺激的血小板中，Fg标记与表面连接小管系统（SCCS）管腔内的致密物质相关。在培养第12天，GPS患者的巨核细胞含有一些标记有Fg和vWF的小α-颗粒，与成熟血小板中发现的颗粒相同。大多数正常大小的α-颗粒部分或完全为空。因此，我们得出结论，在正常α-颗粒中vWF与Fg的分布不同，并且GPS患者未受刺激的血小板在一群仅通过免疫电子显微镜可鉴定为异常α-颗粒的小颗粒中含有Fg和vWF。此外，灰色血小板的SCCS中存在Fg提示α-颗粒内容物的自发释放。
