Dendritic Cells and Type 2 Inflammation

CD4 Th2 lymfocytes producing IL-4, IL-5 and IL-13 are common controllers of type 2 immunity. They respond to allergens and helminthes only when antigen is presented by professional antigen presenting cells like dendritic cells. Dendritic cells express many pattern recognition receptors that can be triggered by type 2 antigens, leading to direct DC activation and Th2 polarization. Alternatively, type 2 stimuli can first trigger barrier epithelial cells that subsequently activate the DCs via release of TSLP, IL-33 and IL-25. It is clear now that also other innate immune cells involved in type 2 immunity such as basophils and ILC2s help DCs to polarize CD4 T cells towards the Th2 direction. In addition to the roles of DCs in priming CD4 Th2 responses, they also control recall responses of memory CD4 Th2 cells to allergens, identifying these cells as important targets for intervention in allergic inflammatory diseases like asthma, dermatitis and rhinitis.