Eosinophilic inflammation assessed by induced sputum in corticosteroid-dependent asthma

Respir Med. 1999 Mar;93(3):183-9. doi: 10.1016/s0954-6111(99)90006-9.


Sputum induction can be used to study airway inflammation in asthmatics. However, it has not been used in patients with corticosteroid-dependent asthma requiring long-term oral corticosteroids. The aim of the study was to assess the number of eosinophils and the levels of eosinophil cationic protein (ECP) in sputum of 17 corticosteroid-dependent asthmatics by comparison with nine mild untreated asthmatics, 10 moderate asthmatics receiving inhaled steroids (ICS) and 11 healthy subjects. In the 17 corticosteroid-dependent asthmatics, we examined sputum eosinophil markers on two occasions and correlated with the control of asthma. Eosinophils were undetectable in controls and were detected in 63.8% of asthmatics. There were no significant differences between the three groups of asthmatics. ECP levels were significantly increased in ICS or corticosteroid-dependent asthmatics by comparison to controls and mild asthmatics. There was no significant difference between ICS and corticosteroid-dependent asthmatics. During follow-up, corticosteroid-dependent asthmatics with a controlled disease had no significant change in eosinophil numbers or ECP levels. On the other hand, corticosteroid-dependent asthmatics with recent exacerbations had a non-significant increase in eosinophil numbers and a significant increase in ECP levels. This study shows that ECP levels may be more accurate than eosinophil numbers in assessing exacerbations in corticosteroid-dependent asthmatics.

MeSH terms

  • Adolescent
  • Adult
  • Aged
  • Anti-Asthmatic Agents / therapeutic use
  • Anti-Inflammatory Agents / therapeutic use
  • Asthma / drug therapy
  • Asthma / pathology*
  • Biomarkers / blood
  • Blood Proteins / analysis*
  • Eosinophil Granule Proteins
  • Eosinophils*
  • Humans
  • Leukocyte Count
  • Middle Aged
  • Pulmonary Eosinophilia / pathology*
  • Ribonucleases*
  • Sputum / cytology*
  • Steroids


  • Anti-Asthmatic Agents
  • Anti-Inflammatory Agents
  • Biomarkers
  • Blood Proteins
  • Eosinophil Granule Proteins
  • Steroids
  • Ribonucleases