This work was supported by the Academy of Finland and the Finnish Antituberculosis Association.
Reproducibility of measurements of exhaled NO, and cell count and cytokine concentrations in induced sputum
Article first published online: 25 DEC 2001
European Respiratory Journal
Volume 16, Issue 2, pages 242–246, August 2000
How to Cite
Purokivi, M. , Randell, J. , Hirvonen, M.-R. and Tukiainen, H. (2000), Reproducibility of measurements of exhaled NO, and cell count and cytokine concentrations in induced sputum. European Respiratory Journal, 16: 242–246. doi: 10.1034/j.1399-3003.2000.16b10.x
- Issue published online: 25 DEC 2001
- Article first published online: 25 DEC 2001
- Cited By
- Inducible nitric oxide synthase;
- sputum induction
Sputum induction is a noninvasive, well-tolerated method for studying airway inflammation. When induction with hypertonic saline is repeated at short time-intervals (<24 h), the cell profile of sputum has not been reproducible. To determine the proper interval between sampling cell profiles and cytokine contents of sputum samples that had been induced 48 h apart, were compared. In addition, the inducible nitric oxide synthase (iNOS) expression of sputum cells was compared to the levels of exhaled nitric oxide (NO).
Sputum induction and measurement of exhaled NO was performed in 31 healthy nonatopic volunteers. Cell differentials were counted. Concentrations of interleukin (IL)-4, IL-6, tumour necrosis factor (TNF)α, eosinophil cationic protein (ECP) were measured in sputum supernatant, and iNOS was determined.
Reproducibility of cell counts was high (r=0.836 total cells, r=0.762 neutrophils, r=0.966 eosinophils, r=0.742 macrophages). IL-4 (r=0.398), IL-6 (r=0.566), TNFα (r=0.658) and ECP (r=0.501) were also less reproducible in healthy volunteers. Consistent with the low levels of NO in the exhaled air (18.5±2.6 ppb and 19.3±2.8 parts per billion (ppb) on the two study days, r=0.976, p=0.0000), expression of iNOS was not detected.
In conclusion, in healthy subjects, induced sputum cell counts are reproducible. Even though the success rate in nonatopic populations is relatively low, sputum induction appears to be a valid method for detecting inflammatory changes within the airways, when being performed 48 h apart.