The use of sputum eosinophils in the evaluation of occupational asthma.
OBJECTIVE
The diagnosis of occupational asthma needs to be made objectively using as many criteria as possible. These include laboratory exposure tests with occupational agent(s), which are only available in specialized centres. Another approach is to monitor peak expiratory flow or methacholine airway responsiveness during periods at work and away from work. However, these measurements are open to misinterpretation when they are not performed optimally. Airway inflammation is one of the main characteristics of occupational asthma, but is not often assessed during its investigation. The purpose of this work was to review recent studies that have investigated and characterized the changes in sputum cell counts occurring in patients with occupational asthma, in order to evaluate the role of the analysis of sputum cell counts.


RESULTS
There is evidence that monitoring sputum eosinophils can help in the management of asthma. In the majority of cases of occupational asthma, the percentage of sputum eosinophils increases after exposure to occupational agents in the laboratory compared with baseline, but an increase in sputum neutrophils has also been observed. The changes in airway inflammation occurring at the workplace have been less investigated, but indicate that there are significant changes in airway inflammation and especially sputum eosinophils when workers are exposed to a sensitizer at their workplace compared with periods away from the workplace.


CONCLUSIONS
Induced sputum has successfully been used to manage patients with mild to moderate asthma. Its use is promising in occupational asthma, and its role in the investigation of occupational asthma needs to be better defined.
Lemière
Catherine
C
Department of Chest Medicine, Sacré-Coeur Hospital, University of Montreal, Montreal, Quebec, Canada. lemierec@crhsc.umontreal.ca
D001249:Asthma / Q000175:diagnosis* / Q000378:metabolism* / Q000628:therapy; D015415:Biomarkers / Q000032:analysis; D019468:Disease Management; D004804:Eosinophils / Q000378:metabolism*; D006801:Humans; D007958:Leukocyte Count; D009784:Occupational Diseases / Q000175:diagnosis* / Q000378:metabolism* / Q000628:therapy; D011379:Prognosis; D013183:Sputum / Q000166:cytology*
D015415:Biomarkers