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.

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 micrograms, 100 micrograms, 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 (P < 0.02) and the late (P < 0.05) asthmatic reactions. After placebo, mean BH was significantly increased above base line at 24 and 48 h (P < 0.02). After 50 and 100 micrograms salmeterol, BH was less than base line at 24 h and returned to prechallenge values at 48 h. Blood eosinophils increased significantly (P < 0.05) 24 and 48 h after allergen challenge, and no difference was found between treatments. After pretreatment with placebo, serum eosinophil cationic protein (s-ECP) and serum eosinophil protein X (s-EPX) increased significantly (P < 0.05) 24 and 48 h after allergen challenge. After treatment with salmeterol 50 micrograms, s-EPX, but not s-ECP, increased significantly 24 h after challenge, but was normal at 48 h. After salmeterol 100 micrograms, 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.(ABSTRACT TRUNCATED AT 250 WORDS)