Effect of an inhaled corticosteroid on airway eosinophils and allergen-induced airway hyperresponsiveness in dogs.
The presence of airway eosinophils before allergen inhalation may contribute to the development of allergen-induced airway responses. We examined whether a reduction in airway eosinophil numbers before allergen inhalation as a result of inhalation of the corticosteroid budesonide would prevent allergen-induced airway hyperresponsiveness in seven dogs. Acetylcholine airway responsiveness was measured before and 24 h after inhalation of Ascaris suum allergen (10(-6)-10(-2) wt/vol) or its diluent on 4 test days separated by > or = 4 wk. Dogs were pretreated for 7 days before and on the morning of each test day with inhaled budesonide (2.69 mg/day) or a placebo (lactose). Airway eosinophil numbers were assessed by bronchoalveolar lavage. Inhaled budesonide significantly reduced the number of airway eosinophils before allergen inhalation from 3.6 +/- 2.38 x 10(4) (SE) cells/ml after inhaled lactose to 0.3 +/- 0.21 x 10(4) cells/ml after inhaled budesonide (P = 0.028). The decrease in eosinophil number was associated with a significant reduction in allergen-induced airway hyperresponsiveness (P = 0.005). These results support the hypothesis that the number of eosinophils in the airways before allergen inhalation is an important determinant in the development of allergen-induced airway hyperresponsiveness in dogs.
Woolley
M J
MJ
Department of Medicine, McMaster University, Hamilton, Ontario, Canada.
Wattie
J
J
Ellis
R
R
Lane
C G
CG
Stevens
W H
WH
Woolley
K L
KL
Dahlback
M
M
O'Byrne
P M
PM
D000280:Administration, Inhalation; D000403:Airway Resistance / Q000187:drug effects / Q000502:physiology; D000485:Allergens; D000818:Animals; D001992:Bronchoalveolar Lavage Fluid / Q000166:cytology; D001993:Bronchodilator Agents / Q000008:administration & dosage / Q000097:blood / Q000494:pharmacology; D019819:Budesonide; D002452:Cell Count; D004285:Dogs; D004804:Eosinophils / Q000187:drug effects*; D011282:Pregnenediones / Q000008:administration & dosage / Q000097:blood / Q000494:pharmacology*; D012130:Respiratory Hypersensitivity / Q000473:pathology / Q000517:prevention & control*
D000485:Allergens; D001993:Bronchodilator Agents; D011282:Pregnenediones; D019819:Budesonide