Immuno-regulatory cytokines in asthma: IL-15 and IL-13 in induced sputum

Clin Exp Allergy. 2001 Sep;31(9):1441-8. doi: 10.1046/j.1365-2222.2001.01174.x.


Background: The importance of Th2-type lymphocyte function in asthmatic airway inflammation is well recognized, but less is known about the factors which regulate the function of these lymphocytes in asthma. The macrophage-derived cytokine, interleukin (IL)-15 has a number of T cell regulatory properties which might be of relevance to asthma and its treatment.

Objective: The aims were to identify and quantify the T cell regulatory cytokine IL-15 in induced sputum samples from asthmatic patients, in comparison with IL-13, and to relate the levels of these cytokines to treatment with inhaled steroids.

Methods: Induced sputum was collected from 16 asthmatics (eight steroid and eight non-steroid treated) and eight normal controls. IL-15 and IL-13 levels were measured by enzyme-linked immunoassay (ELISA) in sputum. IL-15 levels were also measured in sputum cell culture supernatants and localized to specific sputum cells by immuno-cytochemistry.

Results: IL-15 levels were increased and IL-13 levels were decreased in sputum fluid from steroid-treated compared with non-steroid-treated asthmatics. IL-15 was localized specifically to macrophages and the proportion of these cells expressing IL-15 correlated with sputum fluid IL-15 and IL-15 levels in cell culture supernatants, and all were higher in the steroid-treated asthmatics.

Conclusion: IL-15 and IL-13 production appears to be reciprocally regulated by steroid therapy in asthma patients. The steroid-associated increase in IL-15 may regulate a fundamental shift away from an inflammatory Th2-type environment in asthma and may be an essential component of the cytokine modulation underlying the therapeutic benefit of corticosteroids in this condition.

Publication types

  • Comparative Study
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Adult
  • Anti-Inflammatory Agents, Non-Steroidal / therapeutic use
  • Asthma / drug therapy
  • Asthma / immunology*
  • Asthma / metabolism*
  • Cells, Cultured / chemistry
  • Cells, Cultured / drug effects
  • Cells, Cultured / immunology
  • Cytokines / drug effects*
  • Cytokines / physiology*
  • Female
  • Forced Expiratory Volume / physiology
  • Humans
  • Immunohistochemistry
  • Interleukin-13 / biosynthesis
  • Interleukin-13 / immunology
  • Interleukin-13 / metabolism
  • Interleukin-15 / biosynthesis
  • Interleukin-15 / immunology
  • Interleukin-15 / metabolism
  • Male
  • Middle Aged
  • Sputum / chemistry
  • Sputum / cytology
  • Sputum / immunology
  • Steroids / therapeutic use


  • Anti-Inflammatory Agents, Non-Steroidal
  • Cytokines
  • Interleukin-13
  • Interleukin-15
  • Steroids