I-TAC, also known as CXCL11, is a small cytokine belonging to the CXC chemokine family. It is highly expressed in peripheral blood leukocytes, pancreas and liver, with moderate levels in thymus, spleen and lung and low expression levels were in small intestine, placenta and prostate. The I-TAC chemokine elicits its effects on its target cells by interacting with the cell surface chemokine receptor CXCR3, with a higher affinity than do the other ligands for this receptor, CXCL9 and CXCL1. I-TAC is chemotactic for activated T cells. The CXCL11 gene is located on human chromosome 4 along with many other members of the CXC chemokine family.