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

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 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)