Induced sputum in adolescents with severe stable asthma. Safety and the relationship of cell counts and eosinophil cationic protein to clinical severity

This study examined the safety of sputum induction and the relation between sputum cell counts and clinical parameters in adolescents with severe pers istent asthma. Within 5 days, induced sputum and reversibility in forced expiratory volume in one second (FEV1), quality of life, provocative concentration causing a 20% fall in FEV1 (PC20) of adenosine monophosphate and histamine, exercise -induced bronchoconstriction, overall asthma severity index, and blood eosi nophils were collected in 20 atopic adolescents with moderate-to-severe per sistent asthma (12-18 yrs of age, FEV1 65-110% of predicted, on 500-2,000 m u g inhaled steroids daily). FEV1 was reversible by 13.3+/-2.3% pred, After sputum induction, FEV1 was s till increased by 9.0+/-2.6% pred as compared to the pre-salbutamol baselin e. Sputum contained, median (range): 12.4 (0.4-59.5)% squamous cells, 47.3 (6.8-84.0)% macrophages, 39.0 (4.6-84.8)% neutrophils, 4.8 (1.0-12.4)% lymp hocytes, 0.4 (0-10.8)% eosinophils and 3.6 (0-23.4)% bronchial epithelial c ells. Sputum eosinophils showed a trend towards a significant association w ith the overall asthma severity index (r=0.46, p=0.06) and correlated inver sely with baseline FEV1 (r-0.51, p=0.03). In conclusion, sputum can be induced safely in adolescents with moderate-to -severe persistent asthma, if pretreated with beta(2)-agonists, Despite rel atively low sputum eosinophil counts in these patients on inhaled steroids, the association of eosinophil numbers with baseline forced expiratory volu me in one second and asthma severity index favours a role of induced sputum in monitoring adolescents,vith severe asthma.