July - September 2012: 
Volume 25, Issue 3

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Pneumon 2012, 25(3):283-290
The role of induced sputum in asthma assessment
SUMMARY. During recent years interest has been growing in the use of non-invasive methods for the assessment of airway inflammation in subjects with asthma. To date sputum induction is the only noninvasive measure of airway inflammation that has a clearly proven role in asthma management. Induced sputum cell count and mediator measurements have been particularly well validated. A variety of soluble mediators can be measured in the sputum supernatant of patients with asthma, including eosinophil-derived proteins, cytokines and remodelling-associated proteins. Sputum eosinophilia (i.e., >3%) is a classic feature of asthma, although a minority of patients present a non eosinophilic cellular pattern. The percentage of sputum eosinophils has proved to be useful in predicting short term response to inhaled corticosteroids, and there is scope for the application of other induced sputum markers in clinical practice. Sputum induction is a procedure that is generally well-tolerated and safe and a European Respiratory Society (ERS) Task Force has published a comprehensive review on sputum methodology. The widespread application of induced sputum in the investigation of asthma across the complete spectrum of disease severity, and mainly in moderate to severe asthma, has provided insight into the relationship between airway function and airway inflammation leading to the proposal of new disease phenotypes and the definition of which of these phenotypes respond to current treatment, offering an additional tool to guide the clinical management of patients with asthma. Pneumon 2012, 25(3):283-290.