Blood and sputum eosinophils in COPD; relationship with bacterial load

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Title: Blood and sputum eosinophils in COPD; relationship with bacterial load
Authors: Kolsum, U
Donaldson, GC
Singh, R
Barker, BL
Gupta, V
George, L
Webb, AJ
Thurston, S
Brookes, AJ
McHugh, TD
Wedzicha, JA
Brightling, CE
Singh, D
Item Type: Journal Article
Abstract: BACKGROUND: Sputum and blood eosinophil counts predict corticosteroid effects in COPD patients. Bacterial infection causes increased airway neutrophilic inflammation. The relationship of eosinophil counts with airway bacterial load in COPD patients is uncertain. We tested the hypothesis that bacterial load and eosinophil counts are inversely related. METHODS: COPD patients were seen at stable state and exacerbation onset. Sputum was processed for quantitative polymerase chain reaction detection of the potentially pathogenic microorganisms (PPM) H. influenzae, M. catarrhalis and S. pneumoniae. PPM positive was defined as total load ≥1 × 10(4)copies/ml. Sputum and whole blood were analysed for differential cell counts. RESULTS: At baseline, bacterial counts were not related to blood eosinophils, but sputum eosinophil % was significantly lower in patients with PPM positive compared to PPM negative samples (medians: 0.5% vs. 1.25% respectively, p = 0.01). Patients with PPM positive samples during an exacerbation had significantly lower blood eosinophil counts at exacerbation compared to baseline (medians: 0.17 × 10(9)/L vs. 0.23 × 10(9)/L respectively, p = 0.008), while no blood eosinophil change was observed with PPM negative samples. CONCLUSIONS: These findings indicate an inverse relationship between bacterial infection and eosinophil counts. Bacterial infection may influence corticosteroid responsiveness by altering the profile of neutrophilic and eosinophilic inflammation.
Issue Date: 8-May-2017
Date of Acceptance: 1-May-2017
ISSN: 1465-993X
Publisher: BioMed Central
Journal / Book Title: Respiratory Research
Volume: 18
Issue: 1
Copyright Statement: © The Author(s). 2017.Open Access. This article is distributed under the terms of the Creative Commons Attribution 4.0 International License (, which permits unrestricted use, distribution, and reproduction in any medium, provided you give appropriate credit to the original author(s) and the source, provide a link to the Creative Commons license, and indicate if changes were made. The Creative Commons Public Domain Dedication waiver ( applies to the data made available in this article, unless otherwise stated.
Sponsor/Funder: Medical Research Council (MRC)
Funder's Grant Number: RM63G0377
Keywords: Bacterial infections
COPD exacerbations
Pulmonary eosinophilia
Respiratory System
1102 Cardiovascular Medicine And Haematology
1103 Clinical Sciences
Publication Status: Published
Conference Place: England
Open Access location:
Article Number: 88
Appears in Collections:National Heart and Lung Institute
Airway Disease

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