Concentrations of exhaled nitric oxide in asthmatics and subjects with allergic rhinitis sensitized to the same pollen allergen.
BACKGROUND
Some studies have reported that the levels of exhaled nitric oxide (ENO) in asthmatics are similar to those in subjects with allergic rhinitis, and it has been postulated that atopic status might be the determinant of enhanced nitric oxide production in asthma.


OBJECTIVE
The aim of this study was to determine differences in ENO levels between asthmatics and subjects with allergic rhinitis sensitized to the same allergen, and to correlate these levels with airway responsiveness.


METHODS
Nineteen patients with asthma and 18 subjects with allergic rhinitis monosensitized to Parietaria pollen were enrolled in the study. ENO values and airway responsiveness to methacholine and adenosine 5'-monophosphate (AMP) were measured during the pollen season. The response to each bronchoconstrictor agent was measured by the provocative concentration required to produce a 20% fall in FEV1 (PC20). ENO was measured with the single-exhalation method.


RESULTS
The geometric mean (95% confidence interval) ENO values were significantly higher in asthmatics than in subjects with allergic rhinitis: 72.4p.p.b. (54.9-93.3p.p.b) vs. 44.7p.p.b. (30.9-64.6p.p.b., P = 0.03). In asthmatics, a significant correlation was found between ENO and PC20 AMP values (p = -0.57, P=0.02), whereas no correlation was detected between ENO and PC20 methacholine (p = -0.35, P = 0.14).


CONCLUSIONS
Our results suggest that atopy is not the only determinant of increased ENO levels detected in subjects with asthma, and that responsiveness to AMP may be a more sensitive marker for assessing airway inflammation in asthma compared to methacholine.
Prieto
L
L
Sección de Alergología, Hospital Universitario Dr Peset, Valencia, Spain. prieto_jes@gva.es
Gutiérrez
V
V
Uixera
S
S
Bruno
L
L
D000249:Adenosine Monophosphate; D000328:Adult; D000485:Allergens / Q000276:immunology*; D001249:Asthma / Q000276:immunology / Q000378:metabolism* / Q000503:physiopathology; D001944:Breath Tests / Q000379:methods; D001985:Bronchial Provocation Tests / Q000379:methods; D016085:Bronchoconstrictor Agents; D005260:Female; D005541:Forced Expiratory Volume; D006801:Humans; D008297:Male; D016210:Methacholine Chloride; D009569:Nitric Oxide / Q000378:metabolism*; D032403:Parietaria / Q000276:immunology; D011058:Pollen / Q000276:immunology*; D006255:Rhinitis, Allergic, Seasonal / Q000276:immunology / Q000378:metabolism* / Q000503:physiopathology; D014797:Vital Capacity
D000485:Allergens; D016085:Bronchoconstrictor Agents; D016210:Methacholine Chloride; D009569:Nitric Oxide; D000249:Adenosine Monophosphate