Increased Levels of Airway Neutrophils Reduces the Inhibitory Effects of Inhaled Glucocorticosteroids on Allergen‐Induced Airway Eosinophils
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BACKGROUND: Treatment with inhaled glucocorticosteroids attenuates allergen‐induced airway inflammation but is less effective in people with asthma who have noneosinophilic airway inflammation.OBJECTIVE: Studies in which glucocorticosteroid treatment was used before allergen challenges were re‐examined to determine whether the efficacy of steroid treatment could be predicted by baseline levels of sputum inflammatory cells.PATIENTS AND METHODS: Twenty‐eight nonsmoking subjects with atopic asthma controlled by beta2‐agonists participated in only one of three studies, each carried out with a double‐blind, placebo controlled, randomized, crossover design. Subjects were treated with glucocorticosteroids or placebo for six to eight days and then underwent allergen inhalation challenge. Spirometry was measured for 7 h after allergen challenge, and then sputum inflammatory cells were measured. Sputum inflammatory cells were also measured before and after treatment, and 24 h after allergen challenge. The per cent inhibition of the allergen‐induced airway responses by glucocorticosteroids was calculated.RESULTS: Inhaled gluticocorticosteroids significantly attenuated the early and late asthmatic responses, and the number of allergen‐induced sputum eosinophils (P<0.05). There was a significant negative relationship between the number of sputum neutrophils at baseline, and the per cent inhibition of allergen‐induced sputum eosinophils measured at 7 h (r=‐0.61, P<0.001) and 24 h (r=‐0.73, P<0.0001) after challenge, suggesting that glucocorticosteroids are less effective in attenuating allergen‐induced airway inflammation in subjects with high levels of neutrophils. There was no correlation between the number of sputum eosinophils at baseline and the per cent inhibition of allergen‐induced responses.CONCLUSIONS: Baseline airway neutrophils, not eosinophils, can be used to predict the efficacy of inhaled steroids on allergen‐induced sputum eosinophils.
