CXCL16 is produced by dendritic cells in lymphoid organ T cell zones and bycells in the splenic red pulp both as membrane-bound and soluble forms. Based on northern blot analysis, CXCL16 is also expressed in some non-lymphoid tissues such as lung, small intestine and kidney. The receptor for CXCL16 has been identified as CXCR6 (previously called Bonzo, STRL33 or TYMSTR), which is also a coreceptor for HIV entry. CXCR6 is expressed on naive CD8 cells, natural killer T cells and activated CD8 and CD4 T cells.