Goren M B, Vatter A E, Fiscus J
J Leukoc Biol. 1987 Feb;41(2):111-21. doi: 10.1002/jlb.41.2.111.
Various natural and synthetic substances classified as polyanionics have been implicated in antagonizing phagosome-lysosome fusion in cultured macrophages. The phenomenon has been judged by comparing the transfer of selected markers from secondary lysosomes to phagosomes in control and in "polyanion" cells. Our earlier studies showed that use of one of the markers, the membrane-permeating acridine orange, was plagued with artifacts that were especially misleading in the presence of polyanionic agents. We now question the validity of data obtained by the alternative technique, electron microscopy. Our present evidence shows that nonionic hydrocolloids of sufficiently high molecular weight prevent the transfer of various colloidal electron-opaque markers from lysosomes to phagosomes in the same manner as does the powerful polyanionic "fusion inhibitor" dextran sulfate. Both kinds of hydrocolloids, however, allow delivery of lysosomal, low-molecular-weight highly charged non-permeant fluorescent markers to phagosomes, probably by a fusion process. We propose that neither type of hydrocolloid inhibits fusion; instead, when sufficiently concentrated, they trap particulate electron-opaque markers in a gelatinous matrix, which may move only slowly out of lysosomes. The polyanionics trap the electron-opaque markers physically and acridine orange ionically. Hence, the semblance of "fusion inhibition."
各种被归类为聚阴离子的天然和合成物质都被认为与抑制培养巨噬细胞中的吞噬体-溶酶体融合有关。通过比较对照细胞和“聚阴离子”细胞中选定标记物从次级溶酶体到吞噬体的转移情况来判断这种现象。我们早期的研究表明，使用其中一种标记物——膜通透性吖啶橙时，会受到假象的困扰，在聚阴离子试剂存在的情况下尤其具有误导性。我们现在质疑通过另一种技术——电子显微镜获得的数据的有效性。我们目前的证据表明，分子量足够高的非离子水胶体以与强大的聚阴离子“融合抑制剂”硫酸葡聚糖相同的方式阻止各种胶体电子不透明标记物从溶酶体转移到吞噬体。然而，这两种水胶体都允许通过融合过程将溶酶体中的低分子量、高电荷、非渗透性荧光标记物递送至吞噬体。我们提出，这两种类型的水胶体都不会抑制融合；相反，当浓度足够高时，它们会将颗粒状电子不透明标记物捕获在凝胶状基质中，而这些标记物可能只能缓慢地从溶酶体中移出。聚阴离子通过物理方式捕获电子不透明标记物，而吖啶橙则通过离子方式捕获。因此，出现了“融合抑制”的表象。
