Effect of altered CH2-associated carbohydrate structure on the functional properties and in vivo fate of chimeric mouse-human immunoglobulin G1.
Effect of altered CH2-associated carbohydrate structure on the functional properties and in vivo fate of chimeric mouse-human immunoglobulin G1.
复制标题
CH2相关碳水化合物结构改变的影响对嵌合小鼠 - 人类免疫球蛋白G1的功能特性和体内命运的影响。
DOI：
10.1084/jem.180.3.1087
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发表时间：
1994-09-01
期刊：
影响因子：
--
通讯作者：
Morrison SL
中科院分区：
文献类型：
--
作者：
Wright A;Morrison SL
免疫球蛋白G(Ig G)分子在CH2的Asn297位发生糖基化；结合在那里的N-连接的碳水化合物已被证明有助于抗体(Ab)的稳定性和各种效应功能。结合在Ig G恒定区的碳水化合物是一个复杂的双触角结构。寡糖结构的改变与类风湿性关节炎和骨性关节炎等人类疾病有关。为了研究糖结构改变对抗体效应器功能的影响，我们利用基因转染技术，在中国仓鼠卵巢(CHO)细胞系Lec-1中制备了人-鼠嵌合抗体，该细胞不能通过末端糖基化步骤处理高甘露糖中间产物。我们还在Lec-1亲本的野生型CHO细胞系Pro-5中表达了IgG1抗体。Pro-5产生的抗体(IgG1-Pro-5)与骨髓瘤产生的IgG1-My 1具有相同的特异性，其生物学特性如血清半衰期、影响补体介导的细胞溶解能力和对Fc-Gamma RI的亲和力等。尽管Lec 1产生的抗体IgG1-Lec 1被正确组装并保留了抗原特异性，但它不具有补体介导的溶血作用，并且在补体消耗、C1q结合和C1激活方面明显不足。IgG1-Lec 1与Fc-Gamma R1受体的亲和力降低，但差异显著。在体内，IgG1-Lec 1的半衰期比骨髓瘤或Pro-5产生的对应物更短，更多的在阿尔法阶段被清除，在贝塔阶段更快的清除。酵母源甘露聚糖可抑制IgG1-Lec 1的清除。因此，末端甘露寡糖的存在似乎加速了对IgG1-Lec 1的摄取。因此，某些抗体的功能以及蛋白质在体内的命运受到碳水化合物结构变化的显著影响。在具有明确糖基化突变的细胞系中表达免疫球蛋白被证明是研究糖结构对抗体功能的贡献的有用技术。
Immunoglobulin G (IgG) molecules are glycosylated in CH2 at Asn297; the N-linked carbohydrates attached there have been shown to contribute to antibody (Ab) stability and various effector functions. The carbohydrate attached to the IgG constant region is a complex biantennary structure. Alterations in the structure of oligosaccharide have been associated with human diseases such as rheumatoid arthritis and osteoarthritis. To study the effects of altered carbohydrate structure on Ab effector function, we have used gene transfection techniques to produce mouse-human chimeric IgG1 Abs in the Chinese hamster ovary (CHO) cell line Lec 1, which is incapable of processing the high-mannose intermediate through the terminal glycosylation steps. We also produced IgG1 Abs in Pro-5, the wild-type CHO cell line that is the parent of Lec 1. The Pro-5-produced Ab (IgG1-Pro-5) was similar to IgG1-My 1, a myeloma-produced IgG1 Ab of the same specificity, in its biologic properties such as serum half-life, ability to effect complement-mediated cytolysis, and affinity for Fc gamma RI. Although the Lec 1-produced Ab, IgG1-Lec 1, was properly assembled and retained antigen specificity, it was incapable of complement-mediated hemolysis and was substantially deficient in complement consumption, C1q binding, and C1 activation. IgG1-Lec 1 also showed reduced but significant affinity for Fc gamma R1 receptors. The in vivo half-life of IgG1-Lec 1 was shorter than that of either the myeloma- or Pro-5-produced counterpart, with more being cleared during the alpha-phase and with more rapid clearance during the beta-phase. Clearance of IgG1-Lec 1 could be inhibited by the administration of yeast-derived mannan. Thus the uptake of IgG1-Lec 1 appears to be accelerated by the presence of terminally mannosylated oligosaccharide. Therefore, certain Ab functions as well as the in vivo fate of the protein are dramatically affected by altered carbohydrate structure. Expression of Igs in cell lines with defined glycosylation mutations is shown to be a useful technique for investigating the contribution of carbohydrate structure to Ab function.