Human serum amyloid P component oligomers bind and activate the classical complement pathway via residues 14-26 and 76-92 of the A chain collagen-like region of C1q.


Journal Article

Serum amyloid P component (SAP) was polymerized using the cleavable cross-linker 3,3'-dithio-bis-(sulfo-succinimidylpropionate) to study its interaction with the C system. Dimers and trimers, but no larger oligomers, were observed; the trimers retained native SAP immunoreactivity (except for one calcium-dependent epitope) without displaying neo-SAP epitopes. The SAP trimers bound strongly to C1q, at the level of the collagen-like region (CLR). SAP bound to synthetic C1q A chain peptides 14-26 and 76-92, and these peptides inhibited the binding of SAP trimers to the CLR. When incubated in dilute human serum, SAP trimers consumed total C and C4, but not alternative pathway, hemolytic activities. Consumption of C4 by SAP trimers was inhibited by C1q A chain peptide 14-26. Thus, SAP oligomers bind C1q and activate the classical C pathway via the collagen-like region of C1q, at sites located within residues 14-26 and/or 76-92 of the C1q A chain.

Full Text

Cited Authors

  • Ying, SC; Gewurz, AT; Jiang, H; Gewurz, H

Published Date

  • January 1, 1993

Published In

Volume / Issue

  • 150 / 1

Start / End Page

  • 169 - 176

PubMed ID

  • 8417122

Pubmed Central ID

  • 8417122

Electronic International Standard Serial Number (EISSN)

  • 1550-6606

International Standard Serial Number (ISSN)

  • 0022-1767


  • eng