Kuida K, Tanaka T, Kitamura F, Toyama-Sorimachi N, Miyasaka M
Department of Immunology, Tokyo Metropolitan Institute of Medical Science, Japan.
Int Immunol. 1992 Oct;4(10):1123-8. doi: 10.1093/intimm/4.10.1123.
Although IL-2 receptor beta chain (IL-2R beta) expressed in various lymphoid cell lines binds IL-2 with an intermediate affinity, IL-2R beta expressed in fibroblasts is unable to bind IL-2, suggesting that IL-2R beta is on its own not sufficient for generating the intermediate-affinity receptor and that lymphoid-specific regulatory control may be operated to allow IL-2R beta to bind IL-2. In the present study, we observed that human IL-2R beta expressed in a mouse myeloma X63-Ag8.653 (X63) by cDNA transfection did not bind IL-2, while the same IL-2R beta expressed in an IL-6-dependent mouse B cell hybridoma F12-28, which was obtained by cell fusion between X63 and lipopolysaccharide (LPS)-induced lymphoblasts, bound IL-2 with the intermediate affinity. Interestingly, when the human IL-2R beta cDNA-transfected X63 clone, which by itself manifests no IL-2 binding, was fused with LPS-induced lymphoblasts, the resultant hybridomas manifested intermediate-affinity IL-2 binding. The IL-2 binding was specifically inhibited by addition of antihuman IL-2R beta mAb (Mik-beta 1) but not by mAb against mouse IL-2R subunits, indicating that human IL-2R beta was responsible for the IL-2 binding, i.e. non-functional human IL-2R beta in X63 was converted to competent IL-2R beta by complementation with a mouse spleen cell-derived factor(s) through the cell fusion. Cross-linking experiments with [125I]IL-2 revealed the presence of a 61 kDa protein other than IL-2R beta in cells expressing the intermediate-affinity IL-2R.(ABSTRACT TRUNCATED AT 250 WORDS)
尽管在各种淋巴细胞系中表达的白细胞介素-2受体β链（IL-2Rβ）以中等亲和力结合IL-2，但在成纤维细胞中表达的IL-2Rβ却无法结合IL-2，这表明仅IL-2Rβ自身不足以产生中等亲和力受体，可能存在淋巴细胞特异性调控机制使IL-2Rβ能够结合IL-2。在本研究中，我们观察到通过cDNA转染在小鼠骨髓瘤X63-Ag8.653（X63）中表达的人IL-2Rβ不结合IL-2，而在通过X63与脂多糖（LPS）诱导的淋巴母细胞融合获得的IL-6依赖性小鼠B细胞杂交瘤F12-28中表达相同的IL-2Rβ却以中等亲和力结合IL-2。有趣的是，当自身不表现出IL-2结合能力的人IL-2Rβ cDNA转染的X63克隆与LPS诱导的淋巴母细胞融合时，所得杂交瘤表现出中等亲和力的IL-2结合。添加抗人IL-2Rβ单克隆抗体（Mik-β1）可特异性抑制IL-2结合，而抗小鼠IL-2R亚基的单克隆抗体则无此作用，这表明人IL-2Rβ负责IL-2结合，即X63中无功能的人IL-2Rβ通过与小鼠脾细胞衍生因子通过细胞融合互补而转化为有功能的IL-2Rβ。用[125I]IL-2进行的交联实验表明，在表达中等亲和力IL-2R的细胞中，除了IL-2Rβ外还存在一种61 kDa的蛋白质。（摘要截短于250字）
