Harvill E T, Morrison S L
Department of Microbiology and Molecular Genetics, University of California, Los Angeles 90095, USA.
Mol Immunol. 1996 Aug;33(11-12):1007-14. doi: 10.1016/s0161-5890(96)00027-2.
The alpha subunit of the interleukin-2 (IL-2) receptor (IL-2R alpha)3 has the highest individual affinity for IL-2 and is the only subunit not known to bind other cytokines. The interactions between IL-2 and IL-2R alpha studied in cell binding assays have revealed a number of factors which may vary significantly in different cell lines used for these assays in different laboratories. In order to avoid the problems associated with cellular assays we used an optical biosensor to examine the interaction between IL-2R alpha and hrIL-2. Real-time measurement of association and dissociation resulted in a calculated KD of 1.9 x 10(-7) M for this interaction. We then examined the IL-2R alpha binding of a potentially bivalent IgG3-IL2 fusion protein previously shown to have a higher affinity than hrIL-2 for the high affinity IL-2R but not the intermediate affinity IL-2R. Biosensor measurements of association and dissociation of IgG3-IL2 to IL-2R alpha yielded a similar association rate but a decreased dissociation rate compared to hrIL-2, resulting in a KD of 5.3 x 10(-8) M. This system is applicable to the numerous IL-2 mutants with different affinities and activities and is generalizable to other cytokine/receptor interactions.
白细胞介素-2（IL-2）受体（IL-2Rα）的α亚基对IL-2具有最高的个体亲和力，并且是已知不与其他细胞因子结合的唯一亚基。在细胞结合试验中研究的IL-2与IL-2Rα之间的相互作用揭示了许多因素，这些因素在不同实验室用于这些试验的不同细胞系中可能有显著差异。为了避免与细胞试验相关的问题，我们使用光学生物传感器来检测IL-2Rα与重组人IL-2（hrIL-2）之间的相互作用。结合和解离的实时测量得出这种相互作用的计算解离常数（KD）为1.9×10⁻⁷ M。然后，我们检测了一种潜在的二价IgG3-IL2融合蛋白与IL-2Rα的结合情况，该融合蛋白先前已显示对高亲和力IL-2R的亲和力高于hrIL-2，但对中等亲和力IL-2R的亲和力并非如此。与hrIL-2相比，IgG3-IL2与IL-2Rα结合和解离的生物传感器测量显示结合速率相似，但解离速率降低，得出KD为5.3×10⁻⁸ M。该系统适用于众多具有不同亲和力和活性的IL-2突变体，并且可推广到其他细胞因子/受体相互作用。
