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

van Rensen, E.L.J., Stirling, R.G., Scheerens, J., Staples, Karl J., Sterk, P.J., Barnes, P.J. and Chung, K.F. (2001) Evidence for systemic rather than pulmonary effects of interleukin-5 administration in asthma. Thorax, 56 (12), 935-940. (doi:10.1136/thorax.56.12.935). (PMID:11713356)

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??g) or intravenous (2??g) 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

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Contributors

Author: Karl J. Staples

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