Figure 3. Homeostatic inhibition maintained by homing cues for Tregs.
Antigen presenting cells exposed to environmental cues such as retinoic acid (small intestine) and TGFβ (large intestine) migrate to the mesenteric lymph nodes where they activate naïve T cells. Endothelial cell expression of the corresponding ligands for homing receptors (CCL25 in the small intestine; CCL28 and unknown GPR15 ligand in the large intestine) enable activated T cells expressing unique homing receptors (CCR9 for the small intestine; CCR10 and GPR15 for the large intestine) to home back to the site of antigen capture.