Induced Sputum in the Management of Asthma

Abstract

Historically, researchers have sought evidence for the presence of airway inflammation in sputum. Only the past decade, however, have improvements in the methods of processing sputum turned it into a reliable instrument with good measurement properties. The main refinements have been better separation of sputum from the remainder of the expectorate sputum plus saliva, use of dithiothreitol (DTT) to disperse cells, use of cytospins instead smears, and measurements molecular markers inflammation in the supernatant. Results of studies with this methodology have shown sputum to be a valid, repeatable, and evaluative instrument to directly assess airway inflammation. Because it is noninvasive, this methodology can be applied at random and repeatedly to determine the characteristics of asthma in different situations and to investigate antiinflammatory properties of drugs in clinical trials. This review focuses on preliminary evidence of validity of using sputum examination in the management asthma and other airways diseases. The observations indicate that sputum examination can be useful to document the presence and type of airway inflammation, to predict benefit from corticosteroid treatment, to monitor the effects of treatment in more severe asthma, and to contribute the diagnosis of occupational asthma.

Key Words:

Asthma - induced sputum - sputum eosinophils - eosinophilic bronchitis - sputum cell counts - sputum fluid-phase