Mueller E A, Hamprecht K, Anderer F A
Friedrich-Miescher-Laboratorium, Max-Planck-Gesellschaft, Tübingen, F.R.G.
Immunopharmacology. 1989 Jan-Feb;17(1):11-8. doi: 10.1016/0162-3109(89)90003-9.
Enhancement of human NK cytotoxicity in the presence of fresh Viscum album extract and some commercial V. album extracts Iscador correlated strictly with an increased formation of lytic effector cell/K562 tumor cell conjugates in the single-cell assay. Both activities were completely destroyed by pretreatment of V. album extracts with pectinase, hemicellulase, amyloglucosidase and alpha-glucosidase, but not with proteases and RNase, i.e., the activities are linked to a polysaccharide. The active component in V. album extract was non-dialysable at a molecular weight cutoff of 10,000. Inhibition of both activities was observed with D-galacturonic acid, poly-galacturonic acid and pectins. The site of galacturonic acid-specific interaction could be identified on the effector cells. The rate of effector cell/tumor cell conjugate formation in the presence of V. album extracts, as well as the abrogation of both activities by pretreatment of V. album extracts with exoglycosidases specific for sugars other than galacturonic acid indicated an action of the NK cytotoxicity-enhancing component on the basis of a bridging mechanism. However, no conclusive results could be obtained for the structural specificity of the site interacting with the target cells.
在新鲜的欧洲槲寄生提取物以及一些商业化的欧洲槲寄生提取物（Iscador）存在的情况下，人类自然杀伤细胞（NK）细胞毒性的增强与单细胞试验中溶细胞效应细胞/K562肿瘤细胞结合物形成的增加密切相关。用果胶酶、半纤维素酶、淀粉葡萄糖苷酶和α-葡萄糖苷酶对欧洲槲寄生提取物进行预处理可完全破坏这两种活性，但蛋白酶和核糖核酸酶预处理则不会，即这些活性与一种多糖有关。欧洲槲寄生提取物中的活性成分在截留分子量为10,000时不可透析。D-半乳糖醛酸、聚半乳糖醛酸和果胶可抑制这两种活性。半乳糖醛酸特异性相互作用的位点可在效应细胞上鉴定出来。在欧洲槲寄生提取物存在的情况下效应细胞/肿瘤细胞结合物形成的速率，以及用针对除半乳糖醛酸以外的糖类的外切糖苷酶对欧洲槲寄生提取物进行预处理后这两种活性的消除，表明NK细胞毒性增强成分基于一种桥接机制发挥作用。然而，关于与靶细胞相互作用位点的结构特异性，未能获得确凿结果。
