C3B COVALENTLY BOUND TO IGG DEMONSTRATES A REDUCED RATE OF INACTIVATION BY FACTOR-H AND FACTOR-I
C3B COVALENTLY BOUND TO IGG DEMONSTRATES A REDUCED RATE OF INACTIVATION BY FACTOR-H AND FACTOR-I
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DOI：
10.1084/jem.160.6.1640
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发表时间：
1984-01-01
影响因子：
15.3
通讯作者：
FRANK, MM
中科院分区：
文献类型：
--
作者：
FRIES, LF;GAITHER, TA;FRANK, MM
C3b[补体成分3b]通过C3b.α之间的羟胺敏感键与[人]IgG共价连接。链和位点主要但不排他地位于 IgG H 链中。与游离 C3b 相比，该 C3b 物种表现出对 H 和 I 因子失活的相对抵抗力。这种抗性似乎完全是由于 C3b-IgG 对 H 因子的亲和力降低所致。对失活的抗性并不是通过与另一种类似大小的血清糖蛋白（铜蓝蛋白）结合而赋予 C3b，并且可能是 IgG 的特殊性质。相对于 C3b，C3b-IgG 消耗血清 C3 的能力增强。当 C3b 与 IgG 结合时，这些行为的改变可能部分解释了 IgG 旁路途径活性的增强。此外，IgG 诱导的 C3b 保护可能会影响补体介导的细菌杀伤和吞噬作用，并改变含 IgG 的可溶性免疫复合物的体内处理。
C3b [complement component 3b] was covalently linked to [human] IgG via a hydroxylamine-sensitive bond between the C3b .alpha. chain and sites predominantly, but not exclusively, located in the IgG H chain. This C3b species displays relative resistance to inactivation by factors H and I when compared with free C3b. This resistance appears to be due entirely to reduced affinity of C3b-IgG for factor H. Resistance to inactivation is not conferred on C3b by binding to another serum glycoprotein of similar size, ceruloplasmin, and may be a special property of IgG. C3b-IgG demonstrates an enhanced capacity to consume serum C3 relative to C3b. These alterations of the behavior of C3b when bound to IgG may in part explain the augmentation of alternative pathway activity by IgG. In addition, IgG-induced protection of C3b might influence both complement-mediated killing and phagocytosis of bacteria, as well as modify the in vivo handling of IgG-containing soluble immune complexes.