Ukena T E, Karnovsky M J
Prog Clin Biol Res. 1976;9:261-73.
Transmission and scanning electron microscopy were used to study possible structural correlates in the process of agglutination of several types of normal and transformed cells by Concanavalin A. In parallel studies we found that post-confluence inhibition of cell division and agglutiniability of cells by Concanavalin A were not correlated with patching of surface bound lectin molecules as determined with a hemocyanin marker. Transformed cells growing in monolayer cultures were found to have many more microvilli than the corresponding normal cells. However, when cells were brought into suspension with EDTA, all cells developed numerous microvilli and we were not able to distinguish between agglutinable and nonagglutinable cells on the basis of morphological appearance. Cells agglutinated by Concanavalin A had numerous interdigitated microvilli at points of cell-cell contact. The appearance of spontaneously agglutinated cells and lectin agglutinated cells was very similar with respect to the involvement of microvilli in cell-cell attachments, and labeling studies with hemocyanin indicated that Concanavalin A bound to microvilli is rapidly cleared from these surface specializations in a manner analogous to that observed with patching of surface bound lectin. Several lines of SV-40 transformed fibroblasts were shown to be considerably more spontaneously agglutinable than untransformed cells. These results indicate that Concanavalin A may amplify an intrinsic membrane property common to many transformed cells that is expressed as an increase in the rate of adhesion of suspended cells. It is proposed that the membrane change detected by the agglutination reaction may also be involved in the loss of post-confluence inhibition of cell division and growth of transformed cells in semisolid media, due to a surface interaction that allows transformed cells to use each other as growth substrata.
利用透射电子显微镜和扫描电子显微镜研究了伴刀豆球蛋白A凝集几种正常细胞和转化细胞过程中可能存在的结构关联。在平行研究中，我们发现汇合后细胞分裂的抑制以及伴刀豆球蛋白A对细胞的凝集能力与用血蓝蛋白标记测定的表面结合凝集素分子的成斑现象无关。发现在单层培养中生长的转化细胞比相应的正常细胞有更多的微绒毛。然而，当用乙二胺四乙酸（EDTA）使细胞悬浮时，所有细胞都长出大量微绒毛，我们无法根据形态外观区分可凝集细胞和不可凝集细胞。被伴刀豆球蛋白A凝集的细胞在细胞 - 细胞接触点处有许多相互交错的微绒毛。就微绒毛参与细胞 - 细胞附着而言，自发凝集细胞和凝集素凝集细胞的外观非常相似，并且用血蓝蛋白进行的标记研究表明，与微绒毛结合的伴刀豆球蛋白A以类似于表面结合凝集素成斑所观察到的方式迅速从这些表面特化结构中清除。几株SV - 40转化的成纤维细胞显示出比未转化细胞更易自发凝集。这些结果表明，伴刀豆球蛋白A可能放大了许多转化细胞共有的一种内在膜特性，这种特性表现为悬浮细胞粘附速率的增加。有人提出，凝集反应检测到的膜变化也可能与转化细胞在半固体培养基中汇合后细胞分裂和生长抑制的丧失有关，这是由于一种表面相互作用，使得转化细胞能够将彼此用作生长底物。
