Chemokine (C-X-C motif) ligand 16 (CXCL16) is a small molecular weight cytokine belonging to the CXC family of chemokines, consisting of 254 amino acids and is a type I membrane protein. The gene for human CXCL16 is located on chromosome 17. CXCL16 is produced by dendritic cells within the T-cell zone of lymphoid organs and by cells in the red pulp of the spleen. The inflammatory cytokines IFN-γ and TNF-α induce the expression of CXCL16, which interacts with the chemokine receptor CXCR6 (also known as Bonzo). Injections of folic acid force methylation of CXCL16, inducing high levels of methylation of the CXCL16 gene promoter in the colon, ileum, and lungs, as well as accumulation of iNKT cells in these tissues.