Chopra R K, Powers D C, Kendig N E, Adler W H, Nagel J E
Clinical Immunology Section, National Institute on Aging, Baltimore, MD 21224.
Immunol Invest. 1989 Oct;18(8):961-73. doi: 10.3109/08820138909045783.
In this communication the binding characteristics and possible regulatory role of sIL2R were investigated. Soluble IL2R are released or secreted in high concentrations by phytohemagglutinin (PHA) stimulated human lymphoid cells. The addition of sIL2R, purified by gel filtration chromatography, to cultures of PHA stimulated lymphoblasts resulted in a dose-dependent inhibition of [3H]TdR incorporation that could be overcome by the addition of exogenous IL2. Scatchard analysis of IL2 binding demonstrated that the presence of sIL2R did not inhibit ligand interaction with the high affinity IL2R. Immunoprecipitation studies utilizing [125I]IL2 and the non-inhibitory anti-Tac protein antibody 7G7/B6 revealed that most of the 125I-labeled IL2 migrated with a protein of approximately 45-50 kDa on SDS/PAGE. Together, these results provide evidence that the sIL2R limits the availability of free IL2 to proliferating cells and down-regulates their response without directly affecting the number or function of the cell bound high affinity IL2R.
在本交流中，研究了可溶性白细胞介素2受体（sIL2R）的结合特性及其可能的调节作用。可溶性白细胞介素2受体由植物血凝素（PHA）刺激的人淋巴细胞以高浓度释放或分泌。将经凝胶过滤层析纯化的sIL2R添加到PHA刺激的淋巴母细胞培养物中，导致[3H]胸苷掺入呈剂量依赖性抑制，而添加外源性白细胞介素2可克服这种抑制。对白细胞介素2结合的Scatchard分析表明，sIL2R的存在并不抑制配体与高亲和力白细胞介素2受体的相互作用。利用[125I]白细胞介素2和非抑制性抗Tac蛋白抗体7G7/B6进行的免疫沉淀研究表明，在SDS/PAGE上，大部分125I标记的白细胞介素2与一种约45 - 50 kDa的蛋白质一起迁移。这些结果共同提供了证据，表明sIL2R限制了游离白细胞介素2对增殖细胞的可用性，并下调其反应，而不直接影响细胞结合的高亲和力白细胞介素2受体的数量或功能。
