Figure 2. T_H17 cells and antitumour immunity.

T helper 17 (T_H17) cells traffic to the tumour microenvironment and are expanded by antigen-presenting cells, such as myeloid dendritic cells (DCs) through interleukin-1 (IL-1) and IL-23. T_H17 cells promote the trafficking and retention of effector T cells and natural killer (NK) cells in the tumour environment, through inducing the production of the chemokines CXC-chemokine ligand 9 (CXCL9) and CXCL10 by primary tumour cells. In addition, T_H17 cells induce the production of CC-chemokine ligand 20 (CCL20) by tumour cells and this leads to the recruitment of CC-chemokine receptor 6 (CCR6)⁺ DCs. Therefore T_H17 cells can promote protective antitumour immunity by inducing the recruitment of pro-inflammatory immune effector cells; TCR, T cell receptor.