CD40 and neoplasm: It is then presented to T cells to initiate the major histocompatibility complex I restricted cytotoxic T lymphocyte response and the major histocompatibility complex II-restricted CD4+ Th1 response.[67] At the same time, dendritic cells also provide the second signal required for T cell activation through costimulatory molecules (CD80/B7-1, CD86/B7-2, CD40, etc.)to initiate an immune response.[68] The combination of dendritic cells and T cells can secrete a large amount of IL-12 and IL-18 to activate T cell proliferation, which is conducive to tumor clearance.