Dendritic cells in allergic disease - innocent bystanders or prime suspects?

Background: Dendritic cells (DC) are potent antigen-presenting cells that have a critical role in regulating immune responses. It is now widely recognized that DC play an important role in allergic diseases in both the initial sensitization phase and in the maintenance of allergic airway inflammation. Methods/Data base: A review of the literature. Results/Conclusion: DC form a close network within the respiratory mucosa, and are rapidly recruited from the circulation in response to allergen challenge. Studies from animal models have indicated that these DC capture allergens from the airway and subsequently prime a T-helper cell type 2 (Th2)-mediated immune response, with the development of airway inflammation. Increased DC numbers are also present in humans with allergic disease and evidence is increasing to suggest that there are functional differences between DC of allergic and normal individuals. While several mechanisms have been proposed to explain how DC are involved in the dysregulated immune response to seemingly harmless allergens in individuals with allergic disease, the exact pathways involved remain to be elucidated. However, it can be seen that DC are one of the central mediators in allergic disease and it will be important to increase our understanding of their role in the allergic setting to provide future therapies.