Molecular mechanisms involved in the migration of epidermal dendritic cells in the skin

The murine epidermis contains two types of dendritic cells (DC), Thy-1⁺ dendritic epidermal T cells (DETC) and Langerhans cells. In this review, we introduce our data obtained using a skin organ culture system to examine the migratory capacity of DETC and Langerhans cells into the epidermis. DETC or Langerhans cells were depleted by topical application of clobetazole propionate (CP) solution onto the murine ears. CP-treated or untreated ear skin was co-cultured with syngeneic (semisyngeneic, or allogenic, in experiments with Langerhans cells) epidermal cell suspension. We found (i) that donor DETC or Langerhans cells migrated into the CP-treated epidermis as well as into untreated epidermis, (ii) that leukosialin Ly48 recognized by monoclonal antibody S11 and TNF-α strongly inhibited donor Langerhans cell migration into the epidermis. We mention other molecules that may participate in the migration of Langerhans cells such as chemotactic cytokines, monocyte chemoattractant protein (MCP)-1, TGF-β and skin-homing molecule, cutaneous lymphocyte-associated antigen (CLA) on Langerhans cells.