Blood eosinophil counts during bronchiolitis are related to bronchial hyper-responsiveness and lung function in early adolescence.

Aim: To assess whether inflammatory markers measured in urine and blood during acute bronchiolitis in infancy were associated with asthma, lung function, bronchial hyper-responsiveness (BHR) and atopy at 11 years of age.

Methods: We included 105 children hospitalised for bronchiolitis during their first year of life. At hospitalisation, urinary (U-) eosinophil protein X, U-leukotriene E4 , U-prostaglandin 9α, 11β-PGF2 and blood eosinophil counts were measured. Ninety-five children (90%) were available for follow-up at 11 years of age.

Results: At follow-up, higher blood eosinophil counts obtained during bronchiolitis were observed in the group with asthma than in the group without asthma (median 0.27 versus 0.09 × 10(9) /L, respectively, p = 0.048). By regression analyses, blood eosinophil counts during the acute bronchiolitis were positively associated with BHR (p = 0.006) and negatively associated with forced expiratory volume in first second (p = 0.025) at 11 years of age. None of the other inflammatory markers were associated with asthma, lung function, BHR or atopy at 11 years of age.

Conclusion: Eosinophil inflammation during bronchiolitis may have a long-term impact on lung function and airway responsiveness. The associations could be related to virus-host interactions during bronchiolitis or to predisposed children.