MCP-1 and MIP-1alpha are most efficient in recruiting T cells into the skin in vivo.

To analyze T cell recruitment by chemokines in vivo, we used SCID mice grafted with human skin onto their backs and human T cells into their peritoneal cavities. rh MIP-1alpha and rh MCP-1, as well as mouse MCP-1, attracted significant amounts of human T cells into human skin grafts, whereas effects of rh RANTES, rh SDF-1, or rh IP-10 were minimal. Human T cells were found in a striking perivascular position exclusively at sites of human endothelium. None of the chemokines recruited human T cells across mouse endothelial barriers. For control purposes, chemokines were injected into the abdominal wall directly above the peritoneal cavity, where human T cells had been injected and were not subjected to flow. At this site all tested chemokines attracted human T cells to an equal extent. In summary, our experiments point towards an important role for MCP-1 and MIP-1alpha as T cell chemoattractants for skin inflammatory conditions.