Background: Leukotrienes and isoprostanes are biomarkers of airway inflammation and oxidative stress that can be detected in exhaled breath condensate (EBC). The aim of this study was to evaluate leukotriene B4 (LTB4) and 8-isoprostane levels in EBC of healthy and asthmatic children with episodic and moderate persistent asthma.

Methods: EBC was collected from 62 children aged 6 to 14 years: 22 healthy children, 30 patients with episodic asthma, and 10 patients with moderate persistent asthma, without preventive treatment at the time of enrolment.

Results: LTB4 concentrations were higher in children with asthma than in healthy controls (50.7 pg/mL vs 13.68 pg/mL, P<.011). The same was true for children with moderate persistent asthma compared to children with episodic asthma (146.9 pg/mL vs 18.85 pg/mL, P<.0001), children with moderate persistent asthma compared to healthy controls (146.9 pg/mL vs 13.68 pg/mL, P<.0001), and children with episodic
asthma compared to healthy controls (P, nonsignificant). EBC concentrations of 8-isoprostane were higher in asthmatic than in healthy children (18.3 pg/mL vs 6.59 pg/mL, P<.026). They were also increased in children with moderate persistent asthma compared to those with episodic asthma (36.25 pg/mL and 12.28 pg/mL, P<.012), and in children with moderate persistent asthma and episodic asthma compared to healthy controls (36.25 pg/mL vs 6.59 pg/mL [P<.0001] and 12.28 pg/mL versus 6.59 pg/mL [P<.0001], respectively).

Conclusion: LTB4 and 8-isoprostane concentrations were increased in asthmatic children compared to healthy individuals, with differences detected for 2 degrees of asthma severity. Our findings suggest that EBC is a noninvasive method for airway inflammation and oxidative stress assessment.

Key words: Asthma. Children. Exhaled breath condensate. Leukotriene. Isoprostane.