McKinnon M, Page K, Uings I J, Banks M, Fattah D, Proudfoot A E, Graber P, Arod C, Fish R, Wells T N, Solari R
Cell Biology Unit, GlaxoWellcome Research and Development, Medicines Research Centre, Stevenage, Hertfordshire, SG1 2NY, United Kingdom.
J Exp Med. 1997 Jul 7;186(1):121-9. doi: 10.1084/jem.186.1.121.
Interleukin 5 (IL-5) is the key cytokine involved in regulating the production and many of the specialized functions of mature eosinophils including priming, adhesion, and survival. We have generated a point mutant of human IL-5, IL-5 (E12K), which is devoid of agonist activity in both a TF-1 cell proliferation assay and a human eosinophil adhesion assay. However, IL-5 (E12K) is a potent and specific antagonist of both these IL-5-dependent functional responses. In both receptor binding and cross-linking studies the wild-type and IL-5 (E12K) mutant exhibit virtually identical properties. This mutant protein was unable to stimulate tyrosine phosphorylation in human eosinophils, and blocked the phosphorylation stimulated by IL-5. In contrast, IL-5 (E12K) is a full agonist in a human eosinophil survival assay, although with reduced potency compared to the wild-type protein. This IL-5 mutant enables us to clearly distinguish between two IL-5-dependent functional responses and reveals distinct mechanisms of receptor/cellular activation.
白细胞介素5（IL-5）是参与调节成熟嗜酸性粒细胞生成及许多特殊功能的关键细胞因子，这些功能包括启动、黏附和存活。我们构建了人IL-5的一个点突变体IL-5（E12K），在TF-1细胞增殖试验和人嗜酸性粒细胞黏附试验中它都没有激动剂活性。然而，IL-5（E12K）对这两种依赖IL-5的功能反应都是一种强效且特异性的拮抗剂。在受体结合和交联研究中，野生型和IL-5（E12K）突变体表现出几乎相同的特性。这种突变蛋白无法刺激人嗜酸性粒细胞中的酪氨酸磷酸化，并且能阻断IL-5刺激的磷酸化。相比之下，在人嗜酸性粒细胞存活试验中，IL-5（E12K）是一种完全激动剂，尽管其效力比野生型蛋白有所降低。这种IL-5突变体使我们能够清楚地区分两种依赖IL-5的功能反应，并揭示受体/细胞激活的不同机制。
