Dissimilarity between seasonal changes in airway responsiveness to adenosine-5'-monophosphate and methacholine in patients with grass pollen allergic rhinitis: relation to induced sputum.
BACKGROUND
In patients with allergic rhinitis, bronchial hyperresponsiveness (BHR) and airway inflammation may increase during pollen exposure. BHR can be assessed by adenosine-5'-monophosphate (AMP) or methacholine challenge. It has been suggested that BHR to AMP is more closely related to airway inflammation than BHR to methacholine. Seasonal allergic rhinitis offers a dynamic model to study changes in BHR and airway inflammation during natural allergen exposure.


METHODS
We measured BHR [provocative concentration causing a 20% fall (PC(20)) in forced expiratory volume in 1 s (FEV(1))] to AMP and methacholine, and induced sputum cells in 16 rhinitis patients before and during the 2001 grass pollen season.


RESULTS
There was a decrease in PC(20) methacholine during pollen exposure (geometric mean PC(20) from 3.22 to 1.73 mg/ml, p = 0.0023), whereas no reduction was observed for PC(20) AMP (p = 0.11). There was no increase in sputum eosinophils [pre: 0.69% (95% confidence interval 0.22-2.07); during: 1.85 (0.55- 5.6), p = 0.31]. Although the correlation of log PC(20) methacholine and log PC(20) AMP at baseline was good (r = 0.76, p = 0.001), individual seasonal changes (doubling concentrations) in PC(20) methacholine were not correlated with changes in PC(20) AMP (rho = 0.21, p = 0.44). There was no correlation between baseline log PC(20) methacholine or seasonal changes in PC(20) methacholine and sputum eosinophils (p > 0.12, all correlations). In contrast, there was a significant correlation between seasonal changes in PC(20) AMP and changes in sputum eosinophils (rho = -0.59, p = 0.025).


CONCLUSIONS
These data show dissimilarity between seasonal changes in PC(20) AMP and methacholine in patients with seasonal allergic rhinitis. Moreover, PC(20) AMP seems to be more closely related to sputum eosinophils than PC(20) methacholine. The clinical significance of this discrepancy is unclear.
Beier
Jutta
J
Pulmonary Department, Internal Medicine, University Hospital, Mainz, Germany. j.beier@3-med.klinik.uni-mainz.de
Beeh
Kai Michael
KM
Kornmann
Oliver
O
Morankic
Emila
E
Ritter
Nicole
N
Buhl
Roland
R
D000249:Adenosine Monophosphate / Q000494:pharmacology*; D000328:Adult; D016535:Bronchial Hyperreactivity / Q000097:blood / Q000276:immunology*; D016085:Bronchoconstrictor Agents / Q000494:pharmacology*; D002452:Cell Count; D004804:Eosinophils / Q000276:immunology; D005260:Female; D005541:Forced Expiratory Volume / Q000276:immunology; D006801:Humans; D008297:Male; D016210:Methacholine Chloride / Q000494:pharmacology*; D008875:Middle Aged; D006109:Poaceae / Q000276:immunology; D011058:Pollen / Q000276:immunology*; D006255:Rhinitis, Allergic, Seasonal / Q000097:blood / Q000276:immunology*; D012621:Seasons; D013183:Sputum / Q000166:cytology* / Q000187:drug effects; D018709:Statistics, Nonparametric
D016085:Bronchoconstrictor Agents; D016210:Methacholine Chloride; D000249:Adenosine Monophosphate