The fact that the immune response to cancer is compromised has been convincingly demonstrated in cancer patients. There are many mechanisms as to how tumours escape immunosurveillance.One of the major mechanisms of tumor escape is the inadequate function of dendritic cells (DC),as APC and DC play a pivotal role in the development of antitumour immunity. Rencent studies indicate that several factors can inhibit the differentiation and maturation of dendritic cells and block their function in tumor. These factors include immunosuppressive cytokines（TGF-β, IL-10, IL-6, VEGF）, gangliosides, indoleamine 2,3-dioxygenase and so on.