Mita S, Tominaga A, Hitoshi Y, Sakamoto K, Honjo T, Akagi M, Kikuchi Y, Yamaguchi N, Takatsu K
Department of Biology, Kumamoto University Medical School, Japan.
Proc Natl Acad Sci U S A. 1989 Apr;86(7):2311-5. doi: 10.1073/pnas.86.7.2311.
Interleukin 5 (IL-5) is a glycosylated polypeptide that acts as a key factor for B-cell growth and differentiation. We demonstrated previously that there are two classes (high and low affinity) of IL-5 receptors on murine chronic B-cell leukemic cells (BCL1-B20). Treatment of surface-bound radiolabeled IL-5 with bivalent crosslinkers identified a polypeptide of Mr 92,500. In this study, we analyzed characteristics of high-affinity IL-5 receptors on IL-5-dependent early B-cell lines (T-88 and T88-M), mouse myeloma cells (MOPC-104E), and BCL1-B20 cells. All cell lines had two classes of IL-5 binding sites, but T88-M cells bore the highest number of high-affinity receptors. The number of high-affinity IL-5 receptors on BCL1-B20 cells could be up-regulated 3-fold by lipopolysaccharide and down-regulated by IL-5. Disuccinimidyl tartarate crosslinking of 35S-labeled IL-5 to the receptors on the T88-M and lipopolysaccharide-stimulated BCL1-B20 cells revealed two major 35S-labeled components of Mr 92,500 and Mr 160,000, even when the binding of 35S-labeled IL-5 was carried out under high-affinity conditions (100 pM 35S-labeled IL-5). The Mr 92,500 component, but not the Mr 160,000 component, was detected in the lysates of MOPC-104E and T-88 cells, both of which bore a large number of low-affinity receptors and a limited number of high-affinity receptors. The results suggest that the Mr 92,500 component represents the complex of IL-5 with the low-affinity Mr 46,500 receptor, whereas the high-affinity receptor consists of the Mr 46,500 peptide and an additional peptide.
白细胞介素5（IL-5）是一种糖基化多肽，是B细胞生长和分化的关键因子。我们之前证明，小鼠慢性B细胞白血病细胞（BCL1-B20）上存在两类（高亲和力和低亲和力）IL-5受体。用二价交联剂处理表面结合放射性标记的IL-5，鉴定出一种分子量为92,500的多肽。在本研究中，我们分析了依赖IL-5的早期B细胞系（T-88和T88-M）、小鼠骨髓瘤细胞（MOPC-104E）和BCL1-B20细胞上高亲和力IL-5受体的特征。所有细胞系都有两类IL-5结合位点，但T88-M细胞上高亲和力受体数量最多。BCL1-B20细胞上高亲和力IL-5受体的数量可被脂多糖上调3倍，并被IL-5下调。将35S标记的IL-5与T88-M和脂多糖刺激的BCL1-B20细胞上的受体进行酒石酸二琥珀酰亚胺交联，即使在高亲和力条件下（100 pM 35S标记的IL-5）进行35S标记的IL-5结合，也显示出两种主要的35S标记成分，分子量分别为92,500和160,000。在MOPC-104E和T-88细胞的裂解物中检测到分子量为92,500的成分，但未检测到分子量为160,000的成分，这两种细胞都有大量低亲和力受体和少量高亲和力受体。结果表明，分子量为92,500的成分代表IL-5与低亲和力的分子量为46,500的受体的复合物，而高亲和力受体由分子量为46,500的肽和另一种肽组成。
