Validation of leukotriene B4 measurements in exhaled breath condensate.

Objective: To qualitatively validate an enzyme immunoassay to measure leukotriene B4 in exhaled breath condensate. Exhaled breath condensate is a new non-invasive method to monitor airway inflammation.

Subjects: Twenty-two subjects with different lung diseases attended the outpatient clinic on one occasion for exhaled breath condensate collection.

Methods: Samples were pooled together and purified by reverse-phase high-performance liquid chromatography. The fractions eluted were assayed for leukotriene B4 by enzyme immunoassay.

Results: A single peak of leukotriene B4-like immunoreactivity co-eluting with leukotriene B4 standard (retention time: 24 min) was identified by enzyme immunoassay. Reverse phase-high performance liquid chromatography peak of leukotriene B4 was clearly separated from those of 6-trans-leukotriene B4 (retention time: 14 min) and leukotriene B5 (retention time: 18 min) for which the antiserum used in the enzyme immunoassay had the highest cross-reactivity. Leukotriene B4 recovery was 64%.

Conclusions: This study provides evidence for the presence of leukotriene B4 in the exhaled breath condensate and the specificity of the enzyme immunoassay used.