Exhaled nitric oxide in asthmatic and non-asthmatic children: Influence oftype of allergen sensitization and exposure to tobacco smoke

Asthmatic bronchial inflammation is associated with increased nitric oxide concentrations in exhaled air (eNO). Recent data suggest that this effect a rises from atopy. Our aim in this study was to find out whether atopy and s ensitization to particular allergens influences eNO levels. A total of 213 subjects (41 asthmatics and 172 controls) (96 boys and 117 girls, 7.3-14 ye ars of age) were studied. Parents completed a questionnaire that sought inf ormation on their children's respiratory symptoms and exposure to tobacco s moke. Subjects underwent skin-prick tests for the following common allergen s: Dermatophagoides pteronyssinus (Dpt). cat fur. Aspergillus fumigatus, Al ternaria tenuis, mixed grass, mixed tree pollen, Parietaria officinalis, eg g, and cow's milk. eNO was collected in 1-1 mylar bags (exhaled pressure 10 cmH(2)O, flow 58 ml/s) and analyzed by using chemiluminescence. Atopic and nonatopic children without a history of chronic respiratory symptoms had a similar geometric mean eNO (atopics, n = 28, 11.2 p.p.b.; non-atopics, n = 96, 10.0 p.p.b.; mean ratio 1.1, 95% confidence interval [CI]: 0.7-1.6). C onversely, atopic asthmatic subjects had significantly higher eNO values th an non-atopic asthmatic subjects (atopics, n = 25, 24.8 p.p.b.; non-atopics , n = 16, 11.4 p.p.b.; mean ratio 2.2, 95% CI: 1.2-3.9, p = 0.000). In chil dren with rhinitis alone (n = 15) and those with lower respiratory symptoms other than asthma (n = 33), eNO increased slightly, but not significantly, with atopy. eNO levels correlated significantly with Dpt wheal size (r = 0 .51) as well with the wheal size for cat, mixed grass, and Parietaria offic inalis (r = 0.30-0.29). and with the sum of all wheals (r = 0.47) (p = 0.00 0). Subjects sensitized only for Dpt (but not those subjects sensitized onl y for grass pollen or other allergens) showed significantly higher eNO leve ls than non-atopic subjects (16.4 p.p.b. vs. 10.2 p.p.b., mean ratio 1.6, 9 5% CI: 1.1-2.3, p = 0.002). In asthmatic subjects, Dpt sensitization marked ly increased eNO levels (Dpt-sensitized subjects: 28.0 p.p.b.; Dpt-unsensit ized subjects: 12.2 p.p.b.; mean ratio 2.3, 95% CI: 1.5-3.5, p = 0.000). No n-asthmatic Dpt-sensitized subjects also had significantly higher eNO value s than non-asthmatic, non-Dpt-sensitized subjects (14.2 p.p.b. vs. 10.1 p.p .b.; mean ratio 1.4. 95% Cl: 1.1-1.9, p = 0.008). No difference was found b etween eNO levels in asthmatic subjects and control subjects exposed or une xposed to tobacco smoke. In conclusion, eNO concentrations are high in atop ic asthmatic children and particularly high in atopic asthmatics who are se nsitized to house-dust mite allergen.