Sputum induction as a research tool for sampling the airways of subjects with cystic fibrosis
- aDepartment of Medicine, Division of Pulmonary and Critical Care, Stanford University, Stanford, California, USA, bDepartment of Medicine, Division of Pulmonary and Critical Care, University of Washington, Seattle, Washington, USA, cDepartment of Pediatrics, Division of Infectious Disease Children's Hospital and Regional Medical Center, Seattle, Washington, USA
- Dr M L Aitken, Division of Pulmonary and Critical Care Medicine, Box 356522, 1959 NE Pacific Street, Room BB1253, Seattle, WA 98195–6522, USAmoira{at}u.washington.edu
- Received 16 June 2000
- Revision requested 21 September 2000
- Revised 8 November 2000
- Accepted 5 January 2001
Abstract
BACKGROUND Sputum induction (SI) has proved to be a reliable non-invasive tool for sampling inflammatory airway contents in asthma, with distinct advantages over collection of expectorated sputum (ES) and bronchoalveolar lavage (BAL). A study was undertaken to evaluate the safety of SI and to assess if it might be an equally valuable outcome tool in patients with cystic fibrosis (CF).
METHODS The safety of the procedure was examined and sample volume, cell counts, cytokine concentrations, and bacterial culture results obtained by SI, spontaneous ES, and fibreoptic bronchoscopy were compared in 10 adults with CF.
RESULTS SI was well tolerated and was preferred to BAL by all subjects. The mean (SE) sample volume obtained by SI was significantly greater than ES (6.74 (1.46) ml v 1.85 (0.33) ml, p = 0.005). There was no significant difference in the number of cells per ml of sample collected. There was a difference in the mean (SD) percentage of non-epithelial, non-squamous cells collected (67 (28)%, 86 (21)%, and 99 (1)% for ES, SI, and BAL, respectively). These percentage counts were different between ES and both SI and BAL (p=0.03 and p=0.006, respectively). Cell differential counts (excluding squamous cells) from all collection methods were similar (mean (SD) 84 (9)%, 87 (7)%, and 88 (11)% polymorphonuclear cells for ES, SI, and BAL, respectively). The concentrations of interleukin (IL)-8 and tumour necrosis factor (TNF)-α were the same in all three samples when corrected for dilution using urea concentration. The test specific detection rate for recovery of bacteriological pathogens was 79% for SI, 76% for ES, and 73% for BAL.
CONCLUSION SI offers safety advantages over BAL and may be a more representative airway outcome measurement in patients with CF.
