Elevated complement factor H levels in asthmatic sputa

J Clin Immunol. 2013 Feb;33(2):496-505. doi: 10.1007/s10875-012-9807-8. Epub 2012 Oct 17.


Background: The alternative pathway of the complement system is known to play a role in the generation of asthmatic airway inflammation, but its regulatory complement protein, factor H has not been investigated in this disease.

Purpose: Our aim was to determine the local bronchial complement factor H (CFH) levels in asthma, and to investigate its relationship with complement activation, systemic CFH concentrations and clinical characteristics of patients.

Methods: Induced sputum and plasma were collected from 21 healthy and 26 asthmatic subjects, and complement factor H and SC5b-9 concentrations were assessed by ELISA. Total protein concentrations were determined by biuret-reaction based microassay system from induced sputa.

Results: CFH was detectable in 81 % of healthy and 100 % of asthmatic subjects, while SC5b-9 exceeded the detection limit in 62 % of healthy subjects and 85 % of asthmatic patients. Sputum CFH concentrations and CFH/protein ratios were increased in samples from asthmatic patients, and correlated with loss of lung function, asthma control, severity and medication intensity, but not with plasma CFH concentrations. Sputum CFH/protein ratios were in positive correlation also with sputum eosinophilic cell counts in asthma. SC5b-9 concentrations were not higher in the asthmatic sputa, although they correlated with sputum CFH concentrations.

Conclusions: CFH level is elevated on asthmatic airway surface, and may be associated with uncontrolled inflammation in asthma.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Adult
  • Asthma / diagnosis*
  • Asthma / immunology
  • Case-Control Studies
  • Complement Factor H / metabolism*
  • Complement Membrane Attack Complex / immunology
  • Complement Membrane Attack Complex / metabolism
  • Female
  • Humans
  • Male
  • Middle Aged
  • Sputum / cytology
  • Sputum / immunology
  • Sputum / metabolism*


  • Complement Membrane Attack Complex
  • SC5b-9 protein complex
  • Complement Factor H