Chemokine (C-X-C motif) ligand 16 (CXCL16) is a small cytokine belonging to the CXC chemokine family. Larger than other chemokines (with 254 amino acids), CXCL16 is composed of a CXC chemokine domain, a mucin-like stalk, a transmembrane domain and a cytoplasmic tail containing a potential tyrosine phosphorylation site that may bind SH2. These are unusual features for a chemokine, and allow CXCL16 to be expressed as a cell surface bound molecule, as well as a soluble chemokine. CXCL16 is produced by dendritic cells found in the T cell zones of lymphoid organs, and by cells found in the red pulp of the spleen. Cells that bind and migrate in response to CXCL16 include several subsets of T cells, and natural killer T (NKT) cells. CXCL16 interacts with the chemokine receptor CXCR6, also known as Bonzo.