C-C motif chemokine 17 (CCL17) is a 71 amino acid Cys-Cys chemokine that plays important roles in T cell development in the thymus as well as in trafficking and activation of mature T cells. It is also known as thymus and activation regulated chemokine (TARC). CCL17 is a ligand for the G protein coupled receptors CCR4 and CCR8, and induces chemotactic migration of T lymphocytes, but not monocytes or granulocytes. CCL17 is expressed at high levels in the thymus and at low levels in the lung, colon and small intestine. CCL17 is induced by phytohemagglutinin in the peripheral blood mononuclear cells and by cytokines in monocytes. Cytokines are a family of secreted proteins involved in immunoregulatory and inflammatory processes. The CC chemokines are chemotactic cytokines characterized by two adjacent cysteines that induce directed chemotaxis in nearby responsive cells. Recombinant human CCL17 from Molecular Innovations is provided as a native untagged protein. This chemokine is expressed in E. coli then processed, refolded and purified to yield the native, secreted form of the mature chemokine. >98percent pure by SDS-PAGE, HPLC, MALDI-MS and NMR analysis. CCR4 activity verified by chemotaxis using HH cells. Add deionized water to desired volume, aliquot and freeze unused portion.