CCL20, also known as LARC (Liver and Activation-regulated Chemokine) and Exodus-1, is one of many novel beta chemokines identified through bioinformatics. CCL20 cDNA encodes a 96 amino acid (aa) residue precursor protein with a 26 aa residue signal peptide that is predicted to be cleaved to form the 70 aa residue mature secreted protein. CCL20 is distantly related to other beta chemokines (20 - 28% aa sequence identity) and the gene for CCL20 has been mapped to chromosome 2 rather than 17.
CCL20 has been shown to be expressed predominantly in lymph nodes, appendix, PBL, fetal liver, fetal lung and several cell lines. The expression of CCL20 is strongly up-regulated by inflammatory signals and down-regulated by the anti-inflammatory cytokine IL-10. Synthetic or recombinant CCL20 has been shown to be chemotactic for lymphocytes and to inhibit proliferation of myeloid progenitors in colony formation assays. CCL20 has now been shown to be a unique functional ligand for CCR6 (previously referred to as GPR-CY4, CKR-L3, or STRL22 orphan receptor), a chemokine receptor that is selectively and highly expressed in human dendritic cells derived from CD34+ cord blood precursors.
