METHODS: 231 children spanning 3 months to 20 years of age wheeze and asthma resistant to guidelines-based treatment had bronchoscopy with BAL for granulocyte counts and pathogens in the lower respiratory air spaces, systemic markers of inflammation, and lung function.
RESULTS: Infants ≤ 12 months (n =15) had the highest prevalance of anatomic anomalies (73%), positive BAL pathogens (89%), and BAL neutrophilia (89%). Many children 1-5 years (n = 95) met criteria for asthma (53%), but anatomic anomalies were common (61%) with frequent BAL neutrophilia either isolated (41%) or with eosinophilia (10%), and prevalent BAL pathogens (56%). Children 6-11 years (n=73) primarily had asthma (96%), with heterogenous BAL granulocyte patterns, prevalent allergen sensitization (65%), blood eosinophilia (51%), airflow limitation (42%), and relatively fewer BAL pathogens (46%). Adolescents 12-18 years (n=48) mostly had asthma (96%), with the highest prevalence of pauci-granulocytic BAL (67%), the highest allergen sensitization (75%), lower blood eosinophilia (31%), the greatest prevalence of airflow limitation (56%), and few BAL pathogens (15%).
CONCLUSIONS: In children with problematic wheeze and asthma, common patterns of air space and systemic inflammation differ with maturation. In pre-school children anatomic anomalies and BAL neutrophilia with infection predominate, whereas by school-age children with asthma have heterogeneous air space granulocyte patterns informed by allergens, pathogens, and corticosteroid treatment.