Dendritic cells in asthma

• Dendritic cells (DCs) are essential for inducing Th2 immunity to several allergens.
• Similar to other organs, lung DCs are a heterogeneous population of cells.
• Epithelial cells play a major role in activating DCs in response to inhaled allergens.
• Allergens can also directly activate DCs through pathogen associated molecular patterns (PAMPs).
• DCs also play a central role in inducing tolerance in response to allergens.

The lungs are constantly exposed to antigens, most of which are non-pathogenic and do not require the induction of an immune response. Dendritic cells (DCs) are situated at the basolateral site of the lungs and continuously scan the environment to detect the presence of pathogens and subsequently initiate an immune response. They are a heterogeneous population of antigen-presenting cells that exert specific functions. Compelling evidence is now provided that DCs are both sufficient and necessary to induce allergic responses against several inhaled harmless allergens. How various DC subsets exactly contribute to the induction of allergic asthma is currently a subject of intense investigation. We here review the current progress in this field.