Sela B A, Wang J L, Edelman G M
Proc Natl Acad Sci U S A. 1975 Mar;72(3):1127-31. doi: 10.1073/pnas.72.3.1127.
Normal and immune sera from various animal species were fractionated on columns of Sepharose covalently coupled with the glycoprotein fetuin. Elution of the material bound to fetuin yielded low but reproducible amounts of protein, ranging from 0.02 to 0.2% of the protein mass of the input sera. This material has been identified by immunoelectrophoresis in agar and by zone electrophoresis on cellulose acetate as immunoglobulin. The Ig fractions bound and agglutinated erythrocytes of various species, and also bound to cells from various mouse tissues including heart, kidney, thymus, and spleen. In all cases, the binding was inhibited by glycoproteins such as fetuin and thyroglobulin, by a glycopeptide isolated from fetuin, and by some bacterial lipopolysaccharides. When the binding of these Ig fractions to mouse splenocytes was tested in the presence of 17 saccharides, no inhibition of binding was observed except by sialic acid, D-galactose, N-acetyl-D-glucosamine, and D-mannose, all of which showed partial inhibition. Inasmuch as these four saccharides are present on the carbohydrate moiety of fetuin, the results suggest that the isolated material is a carbohydrate-specific Ig (CS-Ig) fraction of serum capable of binding to the carbohydrate portion of cell surface receptors and glycoproteins. When bound to lymphocytes, these CS-Ig molecules induced redistribution (patching and capping) of cell surface receptors. Moreover, the CS-Ig fractions from chicken and rabbit sera were weakly mitogenic for mouse splenic lymphocytes. CS-Ig fractions are useful new reagents for studying glycoproteins and the interactions and activities of cell surface carbohydrates.
将来自各种动物物种的正常血清和免疫血清在与糖蛋白胎球蛋白共价偶联的琼脂糖柱上进行分级分离。洗脱与胎球蛋白结合的物质得到的蛋白质量较低但具有可重复性，占输入血清蛋白质量的0.02%至0.2%。通过琼脂免疫电泳和醋酸纤维素区带电泳已将该物质鉴定为免疫球蛋白。这些免疫球蛋白组分能结合并凝集各种物种的红细胞，也能与来自各种小鼠组织（包括心脏、肾脏、胸腺和脾脏）的细胞结合。在所有情况下，这种结合都受到诸如胎球蛋白和甲状腺球蛋白等糖蛋白、从胎球蛋白中分离出的一种糖肽以及一些细菌脂多糖的抑制。当在17种糖类存在的情况下测试这些免疫球蛋白组分与小鼠脾细胞的结合时，除了唾液酸、D-半乳糖、N-乙酰-D-葡糖胺和D-甘露糖外，未观察到结合抑制，所有这些糖类均表现出部分抑制作用。由于这四种糖类存在于胎球蛋白的碳水化合物部分，结果表明分离出的物质是血清中一种能与细胞表面受体和糖蛋白的碳水化合物部分结合的碳水化合物特异性免疫球蛋白（CS-Ig）组分。当与淋巴细胞结合时，这些CS-Ig分子会诱导细胞表面受体的重新分布（成斑和帽化）。此外，来自鸡和兔血清的CS-Ig组分对小鼠脾淋巴细胞有微弱的促有丝分裂作用。CS-Ig组分是研究糖蛋白以及细胞表面碳水化合物的相互作用和活性的有用新试剂。
