de Bakker Bärbel I, Bodnár Andrea, van Dijk Erik M H P, Vámosi György, Damjanovich Sándor, Waldmann Thomas A, van Hulst Niek F, Jenei Attila, Garcia-Parajo María F
Applied Optics group, Faculty of Science and Technology, MESA+ Research Institute for Nanotechnology, University of Twente, PO Box 217, 7500 AE Enschede, The Netherlands.
J Cell Sci. 2008 Mar 1;121(Pt 5):627-33. doi: 10.1242/jcs.019513.
Interleukin 2 and interleukin 15 (IL2 and IL15, respectively) provide quite distinct contributions to T-cell-mediated immunity, despite having similar receptor composition and signaling machinery. As most of the proposed mechanisms underlying this apparent paradox attribute key significance to the individual alpha-chains of IL2 and IL15 receptors, we investigated the spatial organization of the receptors IL2Ralpha and IL15Ralpha at the nanometer scale expressed on a human CD4+ leukemia T cell line using single-molecule-sensitive near-field scanning optical microscopy (NSOM). In agreement with previous findings, we here confirm clustering of IL2Ralpha and IL15Ralpha at the submicron scale. In addition to clustering, our single-molecule data reveal that a non-negligible percentage of the receptors are organized as monomers. Only a minor fraction of IL2Ralpha molecules reside outside the clustered domains, whereas approximately 30% of IL15Ralpha molecules organize as monomers or small clusters, excluded from the main domain regions. Interestingly, we also found that the packing densities per unit area of both IL2Ralpha and IL15Ralpha domains remained constant, suggesting a 'building block' type of assembly involving repeated structures and composition. Finally, dual-color NSOM demonstrated co-clustering of the two alpha-chains. Our results should aid understanding the action of the IL2R-IL15R system in T cell function and also might contribute to the more rationale design of IL2R- or IL15R-targeted immunotherapy agents for treating human leukemia.
白细胞介素2和白细胞介素15（分别为IL2和IL15）对T细胞介导的免疫有截然不同的作用，尽管它们具有相似的受体组成和信号传导机制。由于大多数解释这一明显矛盾现象的机制都将关键意义归因于IL2和IL15受体各自的α链，我们使用单分子敏感近场扫描光学显微镜（NSOM），在纳米尺度上研究了在人CD4 +白血病T细胞系上表达的IL2Rα和IL15Rα受体的空间组织。与先前的研究结果一致，我们在此证实了IL2Rα和IL15Rα在亚微米尺度上的聚集。除了聚集之外，我们的单分子数据还显示，不可忽视比例的受体以单体形式存在。只有一小部分IL2Rα分子位于聚集域之外，而大约30%的IL15Rα分子以单体或小簇的形式存在，被排除在主要域区域之外。有趣的是，我们还发现IL2Rα和IL15Rα域每单位面积的堆积密度保持不变，这表明存在一种涉及重复结构和组成的“构建块”类型的组装。最后，双色NSOM证明了两条α链的共聚集。我们的结果应有助于理解IL2R - IL15R系统在T细胞功能中的作用，也可能有助于更合理地设计用于治疗人类白血病的靶向IL2R或IL15R的免疫治疗药物。
