Chemokine (C-C motif) ligand 19 (CCL19), also known as the macrophage inflammatory protein-3-beta (MIP-3-beta), is a protein that in humans is encoded by the CCL19 gene. CCL19 is expressed abundantly in thymus and lymph nodes, with moderate levels in trachea and colon and low levels in stomach, small intestine, lung, kidney and spleen. The gene for CCL19 is located on human chromosome 9. This chemokine elicits its effects on its target cells by binding to the chemokine receptor chemokine receptor CCR7. It attracts certain cells of the immune system, including dendritic cells and antigen-engaged B cells, CCR7+ central-memory T-Cells.