Lymphatic epithelial cells (green) release the chemokine CCL20, resulting in a gradient in the lymph node that acts as a cue for innate-like T lymphocytes with CCR6 receptors on their surface (CCR6+; ochre cells) to migrate toward the subcapsular sinus area (the region of the lymph node where lymph enters the tissue). There, the innate-like T lymphocytes can sense interleukin-1β (IL-1β) that the macrophages that line the sinus (blue cells) release locally in response to the activation of the inflammasome. Together with interleukin-23 (not shown), IL-1β activates the CCR6+ innate-like lymphocytes, which in turn produce interleukin-17 (IL-17). IL-17 is a critical factor for microbial defense because it promotes the recruitment of other innate immune cells – neutrophils and monocytes. The graphical illustration was designed and kindly provided by Karl Komander.