C3b covalently bound to IgG demonstrates a reduced rate of inactivation by factors H and I.


Journal Article

We have prepared C3b covalently linked to IgG via a hydroxylamine-sensitive bond between the C3b alpha' chain and sites predominantly, but not exclusively, located in the IgG heavy 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.

Full Text

Cited Authors

  • Fries, LF; Gaither, TA; Hammer, CH; Frank, MM

Published Date

  • December 1, 1984

Published In

Volume / Issue

  • 160 / 6

Start / End Page

  • 1640 - 1655

PubMed ID

  • 6239898

Pubmed Central ID

  • 6239898

International Standard Serial Number (ISSN)

  • 0022-1007

Digital Object Identifier (DOI)

  • 10.1084/jem.160.6.1640


  • eng

Conference Location

  • United States