Functional studies on dendritic cells in the respiratory tract and related mucosal tissues.

Recent reports indicate that mucosal tissues contain dendritic cell (DC) populations that exhibit phenotypic features distinct from those at more studied sites such as skin. In particular, mucosal DC populations display very rapid baseline turnover rates, which increase in response to local inflammatory stimuli. This property is likely to be central to the role of mucosal DC in surveillance of these front-line tissues for incoming microbial pathogens. As we discuss, it may also indirectly account for the "Th2 default," which is the recognized hallmark of mucosal immune system in the steady state.