贪婪
抗体
受体
细胞溶解
溶解
生物化学
化学
抗体依赖性细胞介导的细胞毒性
分子生物学
单体
氨基酸
效应器
抗原
补语(音乐)
补体系统
生物物理学
体外
补体受体
生物
补体依赖性细胞毒性
免疫系统
免疫学
聚合物
细胞毒性
有机化学
作者
R. I. F. Smith,Maria J. Coloma,Sherie L. Morrison
出处
期刊:Journal of Immunology
[The American Association of Immunologists]
日期:1995-03-01
卷期号:154 (5): 2226-2236
被引量:29
标识
DOI:10.4049/jimmunol.154.5.2226
摘要
Abstract The 18-amino acid carboxyl-terminal tailpiece from IgM (mutp) has now been added to the carboxyl-termini of IgG1, IgG2, IgG3, and IgG4 constant regions to produce recombinant IgM-like IgGs. Polymeric IgGs obtained by this approach possess up to six Fcs and 12 antigen-combining sites, greatly increasing the avidity of their interactions with other molecules. Not surprisingly, the C activity of normally active IgG1 and IgG3 and somewhat less active IgG2 Abs is shown to be dramatically enhanced upon polymerization. The multiple Fcs present in a single molecule apparently allow for more efficient interactions with the multiple C1q heads present in C1, the first component of the classical C cascade. An unexpected result however, is that IgG4, normally devoid of C activity, when polymerized in the same fashion directs C-mediated lysis of target cells almost as effectively as the other polymers. Interestingly though, IgG4mutp does not deplete C activity in a standard consumption assay using soluble Ag. The other gamma mutp isotypes are capable of depleting 100% of the serum lytic ability even in the absence of Ag, whereas IgG4mutp shows no evidence of activity in this assay under any of the conditions tested. Additionally, we show that, in contrast to monomeric IgG, polymeric IgGs bind with very high affinity to Fc gamma receptor II (Fc gamma RII), a low affinity receptor for wild-type antibodies; however, binding to Fc gamma Rl, the high affinity receptor, appears to be unaltered. Finally, the in vivo t1/2 of the gamma mutp proteins is decreased relative to wild-type IgG, apparently because of rapid clearance of the polymeric fraction.
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