Pasternak C, Elson E L
J Cell Biol. 1985 Mar;100(3):860-72. doi: 10.1083/jcb.100.3.860.
Using a recently developed method (Petersen, N. O., W. B. McConnaughey, and E. L. Elson, 1982, Proc. Natl. Acad. Sci. USA., 79:5327-5331), we have measured changes in the deformability of lymphocytes triggered by cross-linking cell surface proteins. Our study was motivated by two previously demonstrated phenomena: the redistribution ("capping") of cross-linked surface immunoglobulin (sIg) on B lymphocytes and the inhibition of capping and lateral diffusion ("anchorage modulation") of sIg by the tetravalent lectin Concanavalin A (Con A). Both capping and anchorage modulation are initiated by cross-linking cell surface proteins and both require participation of the cytoskeleton. We have shown that the resistance of lymphocytes to deformation strongly increased when sIg or Con A acceptors were cross-linked. We have measured changes in deformability in terms of an empirical "stiffness" parameter, defined as the rate at which the force of cellular compression increases with the extent of compression. For untreated cells the stiffness was approximately 0.15 mdyn/micron; for cells treated with antibodies against sIg or with Con A the stiffness increased to approximately 0.6 or 0.4 mdyn/micron, respectively. The stiffness decreased after completion of the capping of sIg. The increases in stiffness could be reversed to various extents by cytochalasin D and by colchicine. The need for cross-linking was demonstrated by the failure both of monovalent Fab' fragments of the antibodies against sIg and of succinylated Con A (a poor cross-linker) to cause an increase in stiffness. We conclude that capping and anchorage modulation involve changes in the lymphocyte cytoskeleton and possibly other cytoplasmic properties, which increase the cellular viscoelastic resistance to deformation. Similar increases in cell stiffness could be produced by exposing cells to hypertonic medium, azide ions, and to a calcium ionophore in the presence of calcium ions. These results shed new light on the capabilities of the lymphocyte cytoskeleton and its role in capping and anchorage modulation. They also demonstrate that measurements of cellular deformability can characterize changes in cytoskeletal functions initiated by signals originating at the cell surface.
运用一种最近开发的方法（彼得森，N. O.，W. B. 麦康纳吉，以及E. L. 埃尔森，1982年，《美国国家科学院院刊》，79:5327 - 5331），我们测量了因细胞表面蛋白交联而引发的淋巴细胞变形能力的变化。我们的研究受到两个先前已证实的现象的推动：B淋巴细胞上交联的表面免疫球蛋白（sIg）的重新分布（“帽化”）以及四价凝集素伴刀豆球蛋白A（Con A）对sIg帽化和侧向扩散的抑制（“锚定调节”）。帽化和锚定调节均由细胞表面蛋白交联引发，且两者都需要细胞骨架的参与。我们已经表明，当sIg或Con A受体交联时，淋巴细胞对变形的抵抗力会显著增加。我们根据一个经验性的“刚度”参数测量了变形能力的变化，该参数定义为细胞压缩力随压缩程度增加的速率。对于未处理的细胞，刚度约为0.15 达因/微米；对于用抗sIg抗体或Con A处理的细胞，刚度分别增加到约0.6或0.4 达因/微米。sIg帽化完成后刚度下降。细胞松弛素D和秋水仙碱可在不同程度上使刚度增加得到逆转。抗sIg抗体的单价Fab'片段以及琥珀酰化Con A（一种较差的交联剂）均未能导致刚度增加，这证明了交联的必要性。我们得出结论，帽化和锚定调节涉及淋巴细胞细胞骨架以及可能其他细胞质特性的变化，这些变化增加了细胞对变形的粘弹性抵抗力。通过将细胞暴露于高渗介质、叠氮离子以及在钙离子存在下的钙离子载体中，也可产生类似的细胞刚度增加。这些结果为淋巴细胞细胞骨架的能力及其在帽化和锚定调节中的作用提供了新的见解。它们还表明，细胞变形能力的测量可以表征由细胞表面信号引发的细胞骨架功能变化。
