Mechanisms of rhinitis.

Mast cell degranulation leads to the release of histamine and a host of other mediators. However, histamine remains preeminent in proffering the vexatious symptoms of allergic rhinitis including itching, sneezing, dripping, and congestion. The mechanisms of symptom production in rhinitis will be reviewed with an eye toward effects on mucosal resident cells such as epithelium, endothelium, and glands, the role of nociceptive and parasympathetic nerves, and the recruitment and activation of leukocytes in the mucosa. The benefits and mechanisms of action of antihistamines, anticholinergic agents, and glucocorticoids will be discussed.