Ginsberg M H, Taylor L, Painter R G
Blood. 1980 Apr;55(4):661-8.
We have measured thrombin-induced secretion of platelet factor 4 antigen (PF4) and simultaneously followed its intracellular translocation by immunofluorescence. In permeable resting platelets, speckled intracellular immunofluorescent staining for PF4 was observed. Addition of thrombin to washed platelets at 22 degrees C resulted in secretion of PF4 and formation of large (approximately 0.5 micrometer) immunofluorescent masses. These masses moved to the cell periphery during secretion and were virtually absent at the conclusion of secretion. Ultrastructural examination of thrombin-treated platelets revealed vacuoles corresponding in size, shape, and time of occurrence to the large immunofluorescent masses of PF4. These vacuoles contained PF4 by immunoferritin staining of frozen thin sections; they therefore appear to represent the ultrastructural counterpart of the large PF4 masses. When intact cells were stained for PF4 after thrombin addition, only 5.6% of the large masses stained. Thus, during secretion, PF4 antigen is consolidated into large closed pools that appear as vacuoles in the electron microscope.
我们已测量了凝血酶诱导的血小板因子4抗原（PF4）的分泌，并同时通过免疫荧光追踪其细胞内转运。在可渗透的静息血小板中，观察到PF4的斑点状细胞内免疫荧光染色。在22℃下向洗涤过的血小板中加入凝血酶，导致PF4分泌并形成大的（约0.5微米）免疫荧光团块。这些团块在分泌过程中移向细胞周边，在分泌结束时几乎消失。对凝血酶处理过的血小板进行超微结构检查发现，存在与PF4的大免疫荧光团块大小、形状和出现时间相对应的空泡。通过对冷冻薄切片进行免疫铁蛋白染色，这些空泡含有PF4；因此它们似乎代表了大PF4团块的超微结构对应物。当在加入凝血酶后对完整细胞进行PF4染色时，只有5.6%的大团块被染色。因此，在分泌过程中，PF4抗原被整合到大型封闭池中，在电子显微镜下表现为空泡。
