Cutting edge: Species specificity of the CC chemokine 6Ckine signaling through the CXC chemokine receptor CXCR3: Human 6Ckine is not a ligand for thehuman or mouse CXCR3 receptors

The CC chemokine known as 6Ckine (SLC, Exodus-2, or TCA4) has been identifi ed as a ligand for CCR7, Mouse 6Ckine has also been shown to signal through mouse CXCR3 and share some of the activities of IFN-gamma inducible protei n Id and monokine induced by IFN-gamma, Nonetheless,human 6Ckine has not be en shown to bind CXCR3 receptor or have angiostatic activity. In this study , we report that human 6Ckine does not induce a calcium flux in either huma n CXCR3 or mouse CXCR3 transfected cells, although it is an equally potent agonist as mouse 6Ckine and human macrophage inflammatory protein-3 beta in human CCR7 transfected cells, Mouse 6Ckine (but not human 6Ckine) is capab le of competing with radiolabeled IFN-gamma inducible protein 10 for human CXCR3, In addition, radiolabeled human 6Ckine does not bind to either human CXCR3 or mouse CXCR3, Together these data suggest that human CC chemokine 6Ckine is not a ligand for the human or mouse CXC chemokine receptor CXCR3.