Systems Biology Department, Center of Molecular Immunology, Calle 216 esq 15, Atabey, Playa, PO Box 16040, La Habana, CP 11600, Cuba.
Immunobiology. 2013 Jan;218(1):105-13. doi: 10.1016/j.imbio.2012.02.009. Epub 2012 Feb 16.
Elucidating the network of interactions established by Interleukin-2 is a key step to understanding its role as a master regulator of the immune system. Binding of this cytokine by specific antibodies gives rise to different classes of immune complexes that boost or inhibit immune responses. The molecular bases of such functional dichotomy are likely related to the nature of the recognized epitopes, making it necessary to perform fine epitope mapping studies. The current work was aimed at developing a versatile platform to do so. This was accomplished by display of human and mouse Interleukin-2 on filamentous phages, together with extensive mutagenesis of both antigens and high throughput screening of binding properties of more than 200 variants. Detailed molecular pictures of the epitopes were thus delineated for four antibodies against either human or mouse Interleukin-2, which refined and, in some cases, modified the conclusions derived from previous mapping studies with peptide libraries. Overlapping surface patches on mouse Interleukin-2 that also coincide with the predicted interface between the cytokine and its receptor alpha chain were shown to be recognized by two monoclonal antibodies that promote enhancement of immune responses, shedding new light on the structural bases of their biological activity. Our strategy was powerful enough to reveal multiple binding details and could be used to map the epitopes recognized by other antibodies and to explore additional interactions involving Interleukin-2 and related cytokines, thus contributing to our understanding of the complex structure-function relationships within the immune system.
阐明白细胞介素-2 建立的相互作用网络是理解其作为免疫系统主调控因子作用的关键步骤。这种细胞因子与特定抗体的结合产生了不同类别的免疫复合物，从而增强或抑制免疫反应。这种功能二分法的分子基础可能与所识别的表位的性质有关，因此有必要进行精细的表位作图研究。目前的工作旨在开发一种通用的平台来实现这一目标。这是通过在丝状噬菌体上展示人源和鼠源白细胞介素-2 来完成的，同时对两种抗原进行广泛的突变，并对 200 多个变体的结合特性进行高通量筛选。因此，针对四种针对人或鼠白细胞介素-2 的抗体，详细描绘了这些抗体的表位的分子图像，从而细化了，并在某些情况下修改了以前使用肽文库进行的映射研究得出的结论。与预测的细胞因子与其受体 alpha 链之间的界面重叠的鼠源白细胞介素-2 上的重叠表面斑块被证明被两种促进免疫反应增强的单克隆抗体所识别，这为它们的生物学活性的结构基础提供了新的认识。我们的策略足够强大，可以揭示多个结合细节，并可用于绘制其他抗体识别的表位，并探索涉及白细胞介素-2 和相关细胞因子的其他相互作用，从而有助于我们理解免疫系统中的复杂结构-功能关系。
