Effect of inhaled interleukin-5 on number and activity of eosinophils in circulation from asthmatics

Clin Immunol. 1999 May;91(2):163-9. doi: 10.1006/clim.1999.4699.


The aim of the present study was to examine the effects of interleukin-5 (IL-5) inhalation on changes in the activity and number of circulating eosinophils, as well as concentrations of serum total IgE, in allergic asthmatics. A randomized double-blind, placebo-controlled study design was employed in which each subject acted as his or her own control. Eight nonsmoking patients with allergic asthma were administered recombinant human IL-5 by nebulization. Total white blood cell counts and differentials, as well as concentrations of ECP and total IgE in serum, were determined before and at 2, 24, and 48 h after inhalation. Our results demonstrated that eosinophil numbers increased from baseline (3.6 +/- 1.1 x 10(5)/ml) to 6.3 +/- 1.2 x 10(5)/ml (P < 0.01) at 24 h and to 5.7 +/- 0.9 x 10(5)/ml (P < 0.01) at 48 h after IL-5 inhalation in asthmatics. Accompanying this significantly increased blood eosinophilia were significantly elevated serum ECP levels. Compared with baseline (6.3 +/- 1.1 ng/ml), ECP levels increased with time following IL-5 inhalation, reaching 17.6 +/- 2.8 ng/ml (P < 0.01) at 24 h and remaining elevated at 48 h (18.1 +/- 2.9 ng/ml, P < 0.01). IL-5 inhalation had no significant effect on levels of serum total IgE, however. These findings provide direct evidence that nebulized IL-5 not only induces a significant blood eosinophilia but also results in the activation of circulating eosinophils. Our data further support the importance of IL-5 in the pathogenesis of bronchial asthma in humans.

Publication types

  • Clinical Trial
  • Randomized Controlled Trial
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Administration, Inhalation
  • Adult
  • Asthma / immunology*
  • Blood Proteins / metabolism
  • Double-Blind Method
  • Eosinophil Granule Proteins
  • Eosinophils / cytology*
  • Female
  • Humans
  • Immunoglobulin E / blood
  • Interleukin-5 / immunology*
  • Interleukin-5 / pharmacology
  • Male
  • Middle Aged
  • Recombinant Proteins / immunology
  • Recombinant Proteins / pharmacology
  • Ribonucleases*


  • Blood Proteins
  • Eosinophil Granule Proteins
  • Interleukin-5
  • Recombinant Proteins
  • Immunoglobulin E
  • Ribonucleases