Cloning of equine chemokines eotaxin, monocyte chemoattractant protein (MCP)-1, MCP-2 and MCP-4, mRNA expression in tissues and induction by IL-4 in dermal fibroblasts

We report the cloning of four equine CC chemokines, eotaxin, monocyte chemo attractant protein (MCP)-1, MCP-2 and MCP-4, which show high levels of iden tity with their respective homologous sequences in other species. Using a m ultiplex RT-PCR, we have studied the constitutive mRNA expression of these four CC chemokines in skin, lung, liver, spleen, jejunum, colon and kidney of normal adult horses and compared this data with the eosinophil counts in the same samples. We demonstrate that eotaxin mRNA is only expressed in je junum and colon, where there are large numbers of eosinophils suggesting th at eotaxin might be recruiting eosinophils in the normal digestive tract of the horse. MCP-1 and MCP-4 are expressed in all tissues whereas MCP-2 is o nly found in some samples of lung, spleen, liver and kidney. We also report the early induction (2 h) of equine eotaxin and MCP-4, and the up-regulati on of MCP-1 by interleukin-4 in dermal fibroblasts, suggesting these chemok ines might be involved in equine skin allergic diseases. (C) 2000 Elsevier Science B.V. All rights reserved.