Abstract
Eicosanoids are mediators of arachidonic acid pathway. Induced sputum (IS) is a non-invasive material from the lower airways; its sampling is well standardized. Advantage of exhaled breath condensate (EBC) is shorter collection time and low protein content, but this is compromised by extreme dilution and inter-individual variation. Both matrices have been introduced for assessment of inflammatory mediators in asthma.
We compared eicosanoids concentration in IS and EBC samples collected according to the current guidelines and estimated redistribution of eicosanoids and their metabolites as a result of sample processing.
EBC was collected from asthmatics using Jaeger ECO Screen I; IS according to the most recent ERS Task Force recommendations. The same validated quantitative mass spectrometry was used for both matrices ecosanoids' measurements. Random IS samples were split to test enzymatic inhibition during solubilisation.
We quantified 29 eicosanoids, including major prostaglandins, leukotrienes, and their metabolites. Average concentration of eicosanoids was 82 [1-400] times lower in EBC than in IS. IS differed form EBC by higher HETE and undetectable LTC4. Conversion of LTB4 into 5-oxo-LTB4 and increase of tetranor-PGEM was observed during IS solubilisation, non-physiological pH prevented these redistributions only partially.
Although processing of IS shifts eicosanoid profile toward metabolites, significant amounts of mediators are present within detection levels of common immunoassays. A strict adherence to the IS collection protocols is recommended to avoid a pre-analytical bias.
In collaboration with U-BIOPRED within the Innovative Medicine Initiative.
- © 2011 ERS
