Differential regulation of alpha and beta chains of C4b-binding protein during acute-phase response resulting in stable plasma levels of free anticoagulant protein S

Blood. 1994 Aug 1;84(3):815-22.

Abstract

Regulation of C4b-binding protein (C4BP) isoforms during acute phase and its relationship to the plasma concentration of free protein S was elucidated. An assay for beta chain containing C4BP (C4BP beta+) was developed and the concentrations of total C4BP, C4BP beta+, total, free, and bound protein S were measured in patients with acute-phase response. Even though total C4BP was increased to 162% (mean value) of controls, the corresponding value of C4BP beta+ was only 122%. In the acute-phase group, total protein S was increased to the same extent as C4BP beta+ (mean value of 124%), whereas free protein S was not decreased. In controls, total and bound protein S correlated with total C4BP and C4BP beta+. However, in the acute-phase group, the correlation between bound protein S and total C4BP was lost, although the correlation between C4BP beta+ and protein S remained. The present results suggest stable levels of free protein S during acute phase to be the result of differential regulation of C4BP alpha- and beta-chain expression, and the concentration of free protein S to be the resulting molar excess of protein S over C4BP beta+. This mechanism ensures functional levels of free anticoagulant protein S despite high levels of C4BP.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Acute-Phase Proteins / metabolism
  • Acute-Phase Reaction*
  • Antibodies, Monoclonal / metabolism
  • Calcium / metabolism
  • Carrier Proteins / blood*
  • Carrier Proteins / chemistry
  • Complement C4b / metabolism
  • Complement Inactivator Proteins*
  • Glycoproteins*
  • Humans
  • Macromolecular Substances
  • Protein S / blood*

Substances

  • Acute-Phase Proteins
  • Antibodies, Monoclonal
  • Carrier Proteins
  • Complement Inactivator Proteins
  • Glycoproteins
  • Macromolecular Substances
  • Protein S
  • Complement C4b
  • Calcium