Modifications of airway responsiveness to adenosine 5'-monophosphate and exhaled nitric oxide concentrations after the pollen season in subjects with pollen-induced rhinitis.
OBJECTIVE
s: To determine the effect of cessation of exposure to pollen on airway responsiveness to adenosine 5'-monophosphate (AMP) in subjects with pollen-induced rhinitis, and to explore the relationship between changes in airway responsiveness and changes in exhaled nitric oxide (ENO) levels.


METHODS
Subjects were studied during the pollen season and out of season.


METHODS
Specialist allergy unit in a university hospital.


METHODS
Fourteen subjects without asthma with pollen-induced rhinitis who showed bronchoconstriction in response to methacholine and AMP during the pollen season and 10 healthy nonatopic control subjects.


RESULTS
In subjects with pollen-induced rhinitis, ENO concentrations, provocative concentration of agonist causing a 20% fall in FEV(1) (PC(20)) methacholine, and PC(20) AMP were determined during the pollen season and out of season. Healthy control subjects were studied during the pollen season. In subjects with allergic rhinitis, PC(20) AMP increased from a geometric mean of 79.4 mg/mL (95% confidence interval [CI], 31.6 to 199.5 mg/mL) during the pollen season to 316.2 mg/mL (95% CI, 158.5 to 400.0 mg/mL) out of season (p = 0.004). The ENO concentrations decreased from 63.1 parts per billion (ppb) [95% CI, 50.1 to 79.4 ppb] during the pollen season to 30.2 ppb (95% CI, 23.4 to 38.0 ppb) out of season (p < 0.001). The ENO concentrations out of pollen season were still significantly increased in subjects with pollen-induced rhinitis when compared with healthy control subjects. There was no relationship between individual changes in ENO levels and changes in either PC(20) methacholine or PC(20) AMP.


CONCLUSIONS
In pollen-sensitive subjects with allergic rhinitis, the cessation of exposure to pollen is associated with a significant reduction of airway responsiveness to inhaled AMP. However, no association was found between allergen-induced changes in ENO values and in airway responsiveness to either direct or indirect bronchoconstrictors. These findings suggest that modifications in ENO and in airway responsiveness are the consequence of different alterations induced by allergen exposure on the lower airways.
Prieto
Luis
L
Sección de Alergología (The NAOMI Project), Hospital Universitario Dr. Peset and Universidad de Valencia, Spain. prieto_jes@gva.es
Uixera
Sonia
S
Gutiérrez
Valentina
V
Bruno
Laura
L
D000249:Adenosine Monophosphate; D000328:Adult; D001944:Breath Tests; D016535:Bronchial Hyperreactivity / Q000503:physiopathology*; D001985:Bronchial Provocation Tests; D016084:Bronchoconstriction / Q000187:drug effects* / Q000502:physiology; D015331:Cohort Studies; D005260:Female; D005541:Forced Expiratory Volume / Q000187:drug effects / Q000502:physiology; D006801:Humans; D008297:Male; D016210:Methacholine Chloride; D009569:Nitric Oxide / Q000378:metabolism*; D011058:Pollen; D006255:Rhinitis, Allergic, Seasonal / Q000503:physiopathology*; D013147:Spirometry
D016210:Methacholine Chloride; D009569:Nitric Oxide; D000249:Adenosine Monophosphate