The effect of salmeterol on the early‐ and late‐phase reaction to bronchial allergen and postchallenge variation in bronchial reactivity, blood eosinophils, serum eosinophil cationic protein, and serum eosinophil protein X

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Abstract
The late asthmatic response to bronchial allergen challenge and the associated increase in nonspecific bronchial reactivity provides a model for studying the acute inflammatory mechanisms in asthmatic airways. In 12 asthmatic patients (aged 22–37 years) with known dual reaction to allergen challenge, salmeterol 50 μg, 100 μg, or placebo was administered as a single dose 10 min before allergen challenge in a double‐blind, randomized order on three different study days 2 weeks apart. The bronchial reactivity (BH) to histamine was measured the day before and 24 and 48 h after allergen challenge. Salmeterol significantly inhibited the early (PPPPP<0.05) 24 and 48 h after allergen challenge. After treatment with salmeterol 50 μg, s‐EPX, but not s‐ECP, increased significantly 24 h after challenge, but was normal at 48 h. After salmeterol 100 μg, no change in s‐EPX or s‐ECP was found. The results showed that salmeterol eliminated the allergen‐induced dual asthmatic reaction and gave protection against increased BH. Measurement of blood eosinophils, s‐ECP, and s‐EPX indicated that salmeterol may modify this inflammatory cell activity, because raised s‐levels of ECP and EPX may be linked to eosinophil activation and granule secretion. In addition to inducing a long‐lasting bronchodilation, salmeterol may influence acute inflammation.