New insights into the pathophysiology of allergic rhinitis.

The immune response to an allergen is dependent on an initial sensitization process, with future exposures triggering a two-part allergic response including an early and a late phase. The process by which an allergen is recognized as such, including which cell types and cytokines are involved in the sensitization process, has become clearer over the last several years. Similarly, the roles of the different preformed mediators responsible for many of the signs and symptoms of the early phase response have been elucidated. Recent work also has shed some light on the multitude of cells and mediators involved in the late-phase reactions, which can lead to priming and long-term inflammation. This article will discuss some of this recent work as well as review the basics behind all of the stages of the allergic response, especially as they apply to the nose and upper airway.