Validity and safety of sputum induction by HS and UTP in asthma patients

In this study, sputum induction was done on 10 healthy subjects and 24 asthma patients. Sputum induced by inhalation of either hypertonic saline [HS] or uridine 5-triphosphate [UTP] was induced in all the studied subjects. Inhaled UTP produced a larger amount of sputum than HS. There were significant differences in oxygen desaturation during the procedure between the two methods and no significant difference in spirometric measurements during the procedure by both methods. Sputum total cell and differential cell counts with a high proportion of eosinophils in asthmatics were similar between specimens obtained by HS and UTP. Therefore, sputum induction either by HS or UTP is noninvasive, relatively safe, reproducible and repeatable measurement. Patients with asthma have a higher proportion of eosinophils in their induced sputum with a significant negative correlation to FEV1% pred. The analysis of induced sputum has a relevant role in the identification and monitoring of airway inflammation