Exhaled breath condensate analysis for noninvasive quantification of airway
inflammation in
asthma is a potentially useful research tool in children. There is an imbalance between T-helper (Th)-2 cells, which secrete
interleukin (IL)-4, and Th1 cells, which secrete
interferon (IFN)-gamma, in
asthma. We measured concentrations of
IL-4 and IFN-gamma in breath condensates of 37 children (11 normal, 12
steroid-naive, and 14
steroid-treated children with
asthma). Exhaled IFN-gamma was significantly lower in
steroid-naive and
steroid-treated children with
asthma compared with normal control subjects (3.7 +/- 0.2 versus 5.1 +/- 0.4 pg/ml, p < 0.01 and 4.1 versus 5.1 pg/ml, p < 0.05). By contrast, mean exhaled
IL-4 was elevated in
asthma (53.7 +/- 4.2 pg/ml) compared with normal children (35.7 +/- 6.2 pg/ml, p < 0.05) and concentrations were lower with
steroid treatment (37.5 +/- 5.6 pg/ml, p < 0.05). Exhaled
IL-4 was significantly lower in children with
asthma on more than 600 microg inhaled
steroid/day. The IL-4/IFN-gamma ratio was significantly greater in children with
asthma compared with control children and the children with
asthma on inhaled
steroid therapy. We have shown for the first time that IFN-gamma and
IL-4 can be assayed in exhaled breath condensate and shows an increased ratio of IL-4/IFN-gamma, consistent with predominance of Th2 cells in airways of children with
asthma. Exhaled breath condensate analysis may have a useful role in studying allergic
inflammation in childhood
asthma.