Chemokine (C-C motif) ligand 20 (CCL20), also known as macrophage inflammatory protein-3α (MIP-3α), is a small cytokine belonging to the CC chemokine family. It is strongly chemotactic for lymphocytes and weakly attracts neutrophils. Cells known to express CCL20 include monocytes, macrophages, microglia and astrocytes, mast cells, keratinocytes, intestinal epithelium, osteoblasts, fibroblasts, endothelial cells, and bronchial epithelial cells.
CCL20 is implicated in the formation and function of mucosal lymphoid tissues via chemoattraction of lymphocytes and dendritic cells towards the epithelial cells surrounding these tissues. CCL20 elicits its effects on its target cells by binding and activating the chemokine receptor CCR6. CCL20 may play a critical role in autoimmune pathogenesis of the central nervous system.