MIG is a dominant lymphocyte-attractant chemokine in lichen planus lesions

Dense accumulation of mononuclear cells (lymphocytes >> macrophages) in the dermal-epidermal interface and a T cell-mediated cytotoxic reaction agains t basal keratinocytes are hallmarks of lichen planus lesions. In this study , we focused on the chemotactic signals responsible for the selective recru itment of these cells. Using in situ hybridization and immunohistochemistry , the expression and localization of the lymphocyte-and/or monocyte/macroph age-attractant CC chemokines macrophage chemoattractant protein-1 (MCP-1), regulated on activation, normal T cell expressed, and secreted (RANTES), ma crophage inflammatory protein-la and -1 beta (MIP-1 alpha/beta), I-309 and the CXC chemokines monokine induced by interferon-gamma (MIG), interferon-g amma-inducible protein-10 interleukin-8 (IL-8), epithelial-derived neutroph il attractant-78, and growth-related oncogene-alpha were investigated, Stro ng mRNA expression of MIG, IP-10, and MCP-1 and moderate mRNA expression of RANTES and MIP-la were detected exclusively within foci characterized by s trong infiltration with CD3(+) lymphocytes (CD4(+) cells > CD8(+) cells) an d CD68(+) macrophages. All other chemokines investigated were minimally exp ressed or absent. With more than 11% of total cells strongly expressing MIG transcripts, this selectively lymphotactic chemokine was by far the domina nt chemokine and thus may significantly contribute to the inflammatory reac tion in lichen planus lesions. According to the mRNA expression profiles, M IG, IP-10, and MCP-1 were expressed by both basal keratinocytes above and m ononuclear cells within the inflammatory foci, Our findings indicate that a set of chemokines composed of IP-10, MCP-1, RANTES, MIP-1 alpha, and espec ially MIG contributes to the cytokine network and preferential trafficking of mononuclear cells to the interface region off lichen planus lesions.