Decay acceleration of the complement alternative pathway C3 convertase

Dennis E. Hourcade, Lynne M. Mitchell, M. Edward Medof

Research output: Contribution to journalArticlepeer-review

10 Scopus citations


An ELISA-based method is described for analyzing the mechanism by which the decay of the alternative pathway C3 convertase is accelerated by C3 regulatory proteins. Using this assay, we show that human decay-accelerating factor (DAF) and factor H are active on mature convertase complexes (C3bBb) but not on their nascent precursor (C3bB). This finding has implications on the mechanisms of action of these two regulators. The complement convertases cleave the serum protein C3, and the resulting C3b activation fragments covalently attach to nearby targets where they direct antigen selection, immune clearance, and cell lysis. Several protein, including the membrane protein DAF, and the serum protein factor H, limit convertase activity by promoting their irreversible dissociation. An understanding of the biochemical mechanisms providing for their activities would be helpful for the therapeutic control of the complement response.

Original languageEnglish
Pages (from-to)167-173
Number of pages7
Issue number1-3
StatePublished - May 1999


  • Complement
  • Convertase
  • DAF
  • Decay-accelerating factor
  • Decay-acceleration
  • Factor B
  • Factor H


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