Mechanisms of nonallergic asthma

A large number of stimuli are capable of triggering asthmatic attacks through mechanisms that do not involve immune pathways. Possible mechanisms involved in increased airway hyperreactivity after exposure to irritant gases, viral infections, exercise, and nonsteroidal anti-inflammatory drugs are presented. Data are reviewed suggesting that alterations in neurogenic control of airways and in airway inflammation appear to be involved in the development of airway hyperreactivity independent of the stimulus.