Leucotriene B4 in fractionated breath condensate: Comparison of bronchial and alveolar concentrations in children

Background: Asthma is a chronic inflammatory diesease of the airways but recent studies have shown that alveoli are also subject of pathophysiological changes. Objectives: This study was undertaken to compare leucotriene B4 (LTB 4 ) concentrations in different parts of the lungs using a new technique of fractionated breath condensate sampling. Methods: In 69 patients (10-17 years, 34 asthmatics, 35 controls) measurements of exhaled nitric oxide (FE NO ), lung function and LTB 4 concentrations in exhaled breath condensate (EBC) were performed. EBC was collected in two different fractions, representing mainly either the airways or the alveoli, using captovolumetry. LTB 4 concentrations were measured using an ELISA. Results: 44% and 49% of the LTB 4 values were below the detection limit. Concentrations of the bronchial fraction correlated significantly with those of the alveolar fraction (r=0.73, p=0.000). Differences between the fractions were not significant in a paired difference test. Subjects with obstructive lung function (n=4) had significantly higher LTB 4 values than subjects with normal lung function (n= 65) (p=0.043, p=0.040, respectively). Asthmatics had significantely higher alveolar but not bronchial LTB 4 values than controls (p=0.005, p=0.232, respectively). There was no relationship between LTB 4 and FE NO values. Conclusions: Differences in LTB 4 concentrations between asthmatics and controls were only measurable in the alveolar but not in the bronchial fraction of EBC. An additional analysis of alveolar inflammation may therefore be possibly useful in asthmatics. However, lab techniques for analysing LTB 4 in EBC need to be improved and easy applicable.