Illustration showing immune response to bacteria in the gut. Epithelial cells release a group of cytokines (signalling molecules) called alarmins. These alarmins induce another group of cells called innate lymphoid cells (ILCs). Here, ILC-2 cells (blue spheres) are shown producing cytokines including interleukin-25 (IL-25, yellow fog), that initiate and amplify the type 2 immune response. ILC-1 cells (orange and blue spheres) are also shown producing interferon gamma (green cloud). Dendritic cells (brown) are immune cells that present pathogens or foreign molecules (antigens) to other cells of the immune system to be eliminated.