Consideration of the origin of airway hyperresponsiveness appears central to understanding
the origin of asthma. Subjects with and without asthma differ both in the ease with which
airway narrowing is produced by inhalation of histamine or methacholine and in the ability to
demonstrate a maximal response to these agents. The latter appears, on present evidence,
to be due to an added mechanism in asthma rather than the absence of a potent inhibitory
process. Airway hyperresponsiveness is probably acquired during life as a result of airway …