We hypothesized that asthmatic patients, regardless of control levels, responded differentially to AMP-BPT and His-BPT, and that greater reduction in airway responsiveness to AMP (esp. responders of AMP-BPT) was associated with significant symptom alleviation. Henceforth, we sought to: 1) compare diagnostic performance and safety of AMP-BPT and His-BPT in different asthma control levels; 2) determine the association between airway responsiveness and asthmatic symptom scores.