Abstract: Psoriasis is a chronic inflammatory and immunologic disease of unknown etiology.It has been found that increased number of dendritic cells (DCs) and effector T-lymphocytes infiltrate skin lesions of psoriasis,indicating that DCs are involved in the inflammatory response in psoriasis.In normal skin,there are mainly three kinds of DCs:epidermal Langerhans cells,dermal myeloid DCs and plasmacytoid DCs.In skin lesions of psoriasis,the three kinds of DCs interact with T cells,keratinocytes and neutrophilic granulocytes,which can induce and aggravate inflammatory responses.In addition,type Ⅰ interferon secreted by plasmacytoid DCs in a Toll-like receptor-dependent manner can enhance the activation of myeloid DCs and release of inflammatory mediators.