Platelet Activation during Antigen-Induced Airway Reactions in Asthmatic Subjects

CHEMICAL mediators derived from basophils or mast cells are considered to have an important role in the pathophysiology of asthma. Studies designed to document this relation, however, have provided inconsistent results. Some investigators have reported elevated plasma histamine levels associated with bronchoconstriction induced by exercise or inhaled antigen,^{1 2} but others have failed to confirm these findings.³ These discordant results may be explained in part by the reported variability in the accuracy of plasma histamine measurements by different laboratories.⁴ Neutrophil chemotactic factors have also been detected in the circulation after antigeninhalation challenge.^{3 5} Although neutrophil chemotactic factor appears to be a useful.