Chest
Volume 130, Issue 4, October 2006, Pages 1157-1164
Journal home page for Chest

Original Research
Repeated Sputum Inductions Induce a Transient Neutrophilic and Eosinophilic Response

https://doi.org/10.1378/chest.130.4.1157Get rights and content

Introduction

Sputum induction is a tool to monitor airway inflammation, yet it may induce by itself a neutrophilic response when repeated within 24 to 48 h. This limits its repeated use in clinical trials.

Objective

We aimed to investigate the induction and resolution of inflammation generated by repeated sputum inductions.

Subjects and design

Sixteen healthy intermittent smokers participated in a study on the short-term effects of smoking. The nonsmoking arm consisted of seven successive sputum inductions with increasing time intervals (3, 6, 12, 24, 48, and 96 h). Inflammatory cellular characteristics and different soluble mediators were investigated.

Measurements and results

The median percentage of sputum neutrophils increased significantly from baseline to 6 h (58.9% [range, 31.8 to 94.2%] to 83.2% [range, 26.7 to 98.3%], respectively). Surprisingly, the percentage of eosinophils also increased significantly from baseline to 6, 12, 24, and 48 h, as follows: 0.3% (range, 0.0 to 1.2%) to 1.7% (range, 0.0 to 15.5%), 2.2% (range, 0.5 to 12.5%), 1.2% (range, 0.0 to 4.8%), and 0.8% (range, 0.0 to 2.8%), respectively. Interleukin-8 increased significantly from baseline to 24 h (1,553 pg/mL [range, 462 to 8,192 pg/mL] to 2,178 pg/mL [range, 666 to 128,544 pg/mL]).

Conclusions

Repeated sputum inductions should preferably be avoided within 48 h. It induces not only a short-lived neutrophilic response but also a prolonged eosinophilic inflammatory response in healthy subjects, possibly by local changes in osmolarity, and subsequent epithelial and/or mast cell activation.

Section snippets

Study Design

In a study of the subacute effects of smoking on inflammation,10 we designed a nonsmoking arm that consisted of seven sputum inductions separated by increasing time intervals (0, 3, 6, 12, 24, 48, and 96 h). Healthy subjects refrained from smoking for 9 days before and during the study period, which was verified by measuring the levels of exhaled carbon monoxide (CO) [< 6 ppm] and urinary cotinine (< 25 ng/mL).

Subjects

The 16 participants were > 40 years of age and had normal lung function, as follows:

Subjects

Clinical characteristics of the subjects are listed in Table 1. All subjects successfully refrained from smoking for 9 days before and during the study period. All subjects tolerated the sputum induction procedure well, and no adverse events were reported during the study period.

Sputum Quality

The quality characteristics of the sputum samples are shown in Table 2. Thirty-four of the 112 sputum samples (30%) could not be evaluated for total and differential cell counts, due to the percentage of squamous cells

Discussion

Sputum induction is a tool to monitor airway inflammation, yet some reports have shown a neutrophilic response when it is repeated within 24 to 48 h. This may limit its repeated use in clinical trials. We aimed to investigate both the induction and resolution of inflammation generated by repeated sputum inductions. The main result of our study was that repeated sputum inductions in healthy subjects generate a prolonged increase in the number of sputum eosinophils. This was not accompanied by an

Acknowledgment

The authors thank M.A. Star-Kroezen, A.J. van der Laan-Boers, and E.M.D.H. Swierenga (Lung Function Department) for the many lung function measurements and sputum inductions they performed; I. Sloots, M. van der Toorn, H.A. Buivenga-Steketee, and J.A. Noordhoek (Laboratory of Pulmonology and Allergology) for all measurements in sputum and blood; M.D.W. Barentsen (Laboratory of Pathology) for the counting of the iNOS-positive macrophages on cytospins; and Drs. R.A. Uges and B. Greijdanus

References (33)

  • FloreaniAA et al.

    Induction of sputum by hypertonic saline does not cause airway inflammation [abstract]

    Am J Respir Crit Care Med

    (1995)
  • PaggiaroPL et al.

    Sputum induction

    Eur Respir J Suppl

    (2002)
  • van der VaartH et al.

    Acute effects of cigarette smoking on inflammation in healthy intermittent smokers

    Respir Res

    (2005)
  • QuanjerPH et al.

    Lung volumes and forced ventilatory flows: Report Working Party Standardization of Lung Function Tests, European Community for Steel and Coal; Official Statement of the European Respiratory Society

    Eur Respir J Suppl

    (1993)
  • NowakD et al.

    Effect of 3 hours of passive smoke exposure in the evening on inflammatory markers in bronchoalveolar and nasal lavage fluid in subjects with mild asthma

    Int Arch Occup Environ Health

    (1997)
  • RutgersSR et al.

    Comparison of induced sputum with bronchial wash, bronchoalveolar lavage and bronchial biopsies in COPD

    Eur Respir J

    (2000)
  • Cited by (0)

    Parts of this study were presented in a poster at the American Thoracic Society 2004 annual meeting.

    This study was funded by AstraZeneca, Lund, Sweden.

    The authors have reported to the ACCP that no significant conflicts of interest exist with any companies/organizations whose products or services may be discussed in this article.

    Reproduction of this article is prohibited without written permission from the American College of Chest Physicians (www.chestjournal.org/misc/reprints.shtml).

    View full text