Platelet Activation and Allergic Asthma

Abstract

To the Editor: Knauer et al. recently demonstrated the occurrence of platelet activation during IgE-mediated acute airway reactions by an increase in plasma platelet factor 4 — an indicator of in vivo platelet activation — after antigen challenge in asthmatic subjects (June 4 issue).¹ The authors observed a biphasic pattern of platelet factor 4 elevation, which had an early rise, a fall, and a subsequent elevation. They proposed that platelet-activating chemical mediators released by basophils or mast cells caused these elevations in plasma. However, other authors have challenged this hypothesis, suggesting that at least the first peak of the elevation . . .