Biomarker reproducibility in exhaled breath condensate collected with different condensers

¹ Dept of Paediatric Pulmonology, Caphri Research Institute, University Hospital Maastricht, Maastricht, the Netherlands; and Dept of Paediatrics, Maasland Hospital, Sittard, the Netherlands
² Dept of Paediatric Pulmonology, Caphri Research Institute, University Hospital Maastricht, Maastricht, the Netherlands
³ Dept of Methodology and Statistics, Caphri Research Institute, Maastricht University, Maastricht, the Netherlands
⁴ Dept of Pharmacology and Toxicology, Maastricht University, Maastricht, the Netherlands
⁵ Dept of Clinical Chemistry and Clinical Proteomics, University Hospital Maastricht, Maastricht, the Netherlands
⁶ Dept of Immunology, University Medical Centre Wilhelmina Children's Hospital, Utrecht, the Netherlands
⁷ Dept of Paediatrics, University Hospital Maastricht, Maastricht, the Netherlands
⁸ Dept of General Practice, Caphri Research Institute, Maastricht University, Maastricht, the Netherlands

^* To whom correspondence should be addressed. E-mail: p.rosias{at}orbisconcern.nl.

	Abstract

Optimal collection and analysis of exhaled breath condensate (EBC) are prerequisites for standardisation and reproducibility of assessments. We aimed to assess reproducibility of EBC volume, hydrogen peroxide, 8-isoprostane, and cytokine measurements using different condensers, including a newly developed glass condenser.

At four points in time, 30 healthy subjects performed sequential EBC collections randomly using four condensers: glass, silicone, EcoScreen®, and an optimised glass condenser. In small EBC samples, hydrogen peroxide was measured by spectrophotometer, 8-isoprostane by enzyme immunoassay, and cytokines by multiplexed xMAP® technology.

The optimised glass condenser yielded significantly more EBC volume (median 2025µL, IQR 1056), reproducibility of EBC volume was comparable with EcoScreen® (19–20 CV%), but was significantly better compared to silicone and glass (29–37 CV%). The new condenser was associated with significantly more detections of hydrogen peroxide, 8-isoprostane, IL-2, IL-4, IL-5, IL-13, and TNF-alpha. Isoprostane concentrations were significantly higher using the new condenser, whereas hydrogen peroxide and cytokine concentrations were not. Reproducibility of biomarkers was equally variable for all condenser types.

In conclusion, significantly more EBC volume and biomarker detections were found using the optimised glass condenser, including higher 8-isoprostane levels. However, biomarker reproducibility in EBC in healthy adults was not influenced by the type of condenser.

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