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Blood and sputum eosinophils in COPD; relationship with bacterial load.pdf (904.79 kB)

Blood and sputum eosinophils in COPD; relationship with bacterial load

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posted on 2017-08-14, 15:02 authored by Umme Kolsum, Gavin C. Donaldson, Richa Singh, Bethan L. Barker, Vandana Gupta, Leena George, Adam J. Webb, Sarah Thurston, Anthony J. Brookes, Timothy D. McHugh, Jadwiga A. Wedzicha, Christopher E. Brightling, Dave Singh
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.

History

Citation

Respiratory Research, 2017, 18:88

Author affiliation

/Organisation/COLLEGE OF MEDICINE, BIOLOGICAL SCIENCES AND PSYCHOLOGY/School of Medicine/Department of Infection, Immunity and Inflammation

Version

  • VoR (Version of Record)

Published in

Respiratory Research

Publisher

BioMed Central

issn

1465-9921

eissn

1465-993X

Acceptance date

2017-05-01

Copyright date

2017

Available date

2017-08-14

Publisher version

https://respiratory-research.biomedcentral.com/articles/10.1186/s12931-017-0570-5

Language

en

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