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. Dendritic cells (brown) are immune cells that present pathogens or foreign molecules (antigens) to other cells of the immune system to be eliminated.