Evidence for systemic rather than pulmonary effects of interleukin-5 administration in asthma

E. L.J. Van Rensen, R. G. Stirling, J. Scheerens, K. Staples, P. J. Sterk, P. J. Barnes, K. F. Chung

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Abstract

Background - Interleukin 5 (IL-5) has an important role in mobilisation of eosinophils from the bone marrow and in their subsequent terminal differentiation. A study was undertaken to determine whether inhaled and intravenous IL-5 could induce pulmonary eosinophilia and bronchial hyperresponsiveness (BHR) independently of these effects. Methods - Nine mild asthmatics received inhaled (15 μg) or intravenous (2 μg) IL-5 or placebo in random order in a double blind, crossover study. Blood samples were taken before and at 0.5, 1, 2, 3, 4, 5, 24, and 72 hours following IL-5 or placebo, and bronchial responsiveness (PC20 methacholine) and eosinophil counts in induced sputum were determined. Results - Serum IL-5 levels were markedly increased 30 minutes after intravenous IL-5 (p=0.002), and sputum IL-5 levels increased 4 and 24 hours after inhaled IL-5 (p<0.05). Serum eotaxin was raised 24 hours after intravenous IL-5 but not after inhaled IL-5 or placebo. Blood eosinophils were markedly reduced 0.5-2 hours after intravenous IL-5 (p<0.05), followed by an increase at 3, 4, 5, and 72 hours (p<0.05). Sputum eosinophils rose significantly in all three groups at 24 hours but there were no differences between the groups. Bronchial responsiveness was not affected by IL-5. Conclusion - The effects of IL-5 appear to be mainly in the circulation, inducing peripheral mobilisation of eosinophils to the circulation without any effect on eosinophil mobilisation in the lungs or on bronchial responsiveness.

Original languageEnglish
Pages (from-to)935-940
Number of pages6
JournalThorax
Volume56
Issue number12
DOIs
Publication statusPublished - 10 Dec 2001
Externally publishedYes

Keywords

  • Asthma
  • Bronchial responsiveness
  • Eosinophil
  • Interleukin 5

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