Urinary leukotriene E4 levels in atopic and non-atopic preschool children with recurrent episodic (viral) wheezing: a potential marker?

Backround: Reliable biological markers for the differentiation of asthma phenotypes in preschool children with wheezing are lacking. The purpose of the study is to assess the relationship of urinary Leukotriene E4 (U-LTE4) to particular asthma phenotypes in preschool children with recurrent episodic (viral) wheezing following upper respiratory tract infections with or without atopic predisposition. Methods: Ninety-six preschool patients with recurrent episodic wheezing participated, 52 atopic and 44 non-atopic, during exacerbation and in remission. Exacerbation was defined on clinical basis (wheeze in the presence of coryzal symptoms). Atopy was determined by specific serum IgE measurement and skin-prick testing. U-LTE4 was determined by enzyme immunoassay. Thirty-six age-matched, non-asthmatic, non-atopic children served as controls. Results: During exacerbation, U-LTE4 was significantly higher in all children with recurrent episodic wheezing in comparison to A: Remission: 642.20 +/- 268 versus 399.45 +/- 204, p value <0.001 and B: Controls: 642.20 +/- 268 versus 271.39 +/- 83, p value <0.001. Atopic patients demonstrated significantly higher levels of U-LTE4 compared to non-atopic, both during exacerbation 872.13 +/- 246 versus 613.15 +/- 150, p value = 0.0013 and during remission 507.59 +/- 182 versus 283.59 +/- 160, p value 50.001. During remission, a highly significant difference of U-LTE4 was found when controls were compared to atopic patients: 271.39 +/- 83 versus 507.59 +/- 182, p value = 0.002 but not when compared to non-atopic ones: 271.39 +/- 83 versus 283.59 +/- 160, p value = 0.432. Conclusion: U-LTE4 is strongly associated with the acute wheeze episode in preschool children, more so in atopics. Increased basal levels of U-LTE4 occur only in atopics. This suggests a potential role of U-LTE4 as a marker of atopic, virus-induced asthma in preschool children.