Fig. 2.

Role of immature dendritic cells (iDCs) in immune response to foreign pathogens and tumour immunity. (a) General roles of iDCs in immune response to foreign pathogens. The iDCs reside in peripheral tissues, peripheral blood DCs (PBDCs) engulf foreign antigens, which are rapidly activated and matured by pathogen signals, and migrate to lymph node in which mature DCs present foreign antigens to naive T cells that are differentiated to effector T cells, resulting in elimination of the pathogens. (b) Differential functional roles of tumour immature dendritic cells (TiDCs) and newly produced iDCs from bone marrow, which are not primed with apoptotic cells. The newly induced iDCs by granulocyte–macrophage colony-stimulating factor (GM-CSF) and G-CSF from CD34⁺ progenitor cells in bone marrow (BM), bone marrow derived DCs (BMDCs), and the potential iDCs released from compartmentalization within the tumour site can be primed with massive dead cells with inflammatory cytokines following neoadjuvant chemotherapy. These iDCs are activated and matured and migrate to sentinel lymph node (SLN) where they present tumour antigens (TAs) to naive T cells, resulting in proliferation of antigen-specific effector T cells that contribute to tumour response.