Epithelial responses in airway inflammation and immunity

Summary The epithelium is thought to serve an important barrier function in the airways. However, growing evidence now supports the notion that the respiratory epithelium plays a key role in host responses to infectious and allergenic stimuli. The epithelium functions to produce a variety of proinflammatory cytokines during the inflammatory response. More recently, the epithelium has been shown to express a variety of receptors that can recognize microorganisms, such as toll‐like receptors (TLRs), as well as complement and acute phase proteins. Additionally, the cell surface of epithelial cells have also been shown to express a variety of costimulatory molecules which may be involved in regulating the activation of antigen‐specific T cells in the airways. This paper reviews the novel ways by which the epithelium may function in both the innate and adaptive immune responses of the airways.