Determination of serum levels of complement component C4b-binding protein: influence of age and inflammation

Santica M. Marcovina, Adele Zoppo, Silvana Viganó-D'Angelo, Giovanni Di Cola, Armando D'Angelo

Research output: Contribution to journalArticlepeer-review


C4b-binding protein (C4b-BP) is a high molecular weight plasma protein which inhibits the activity of the classical complement pathway C3 convertase. In addition to multiple binding sites for C4b, C4b-BP possesses a single binding site for vitamin K-dependent protein S, an inhibitor of blood coagulation. As protein S bound to C4b-BP has no anticoagulant activity, C4b-BP participates in the regulation of both the complement and the coagulation pathways. We have produced and immunochemically characterized a series of murine monoclonal antibodies to human C4b-BP. A mixture of four monoclonal antibodies precipitating C4b-BP both in agarose gel and in solution was used to develop a highly reproducible radial immunodiffusion method for the measurement of C4b-BP in human serum. C4b-BP levels were measured in sera from 284 patients referred to our central laboratory. Samples from subjects with an increased erythrocyte sedimentation rate (ESR), a1-acid glycoprotein (a1-AGP) or C-reactive protein (CRP) had significantly higher C4b-BP levels (307 mg/l, 292-322 mg/l, geometric mean and 95% confidence limits of the mean) than those from subjects without elevation of the aforementioned established acute phase reactants (231 mg/l, 226-237 mg/l, P

Original languageEnglish
Pages (from-to)171-175
Number of pages5
JournalInternational Journal of Clinical & Laboratory Research
Issue number2-4
Publication statusPublished - Jun 1992


  • Age dependency
  • C4b-binding protein
  • Inflammation
  • Monoclonal antibodies
  • Radial immundiffusion

ASJC Scopus subject areas

  • Clinical Biochemistry


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