A model system using tape stripping for characterization of Langerhans cell-precursors in vivo.

Little is known about the immigration of bone marrow-derived progenitors of Langerhans cells (LC) into the epidermis. We developed an in vivo system based on the tape stripping method that allowed us to study the immigration of LC into the epidermis after intradermal injection of bone marrow-derived dendritic cells (DC). Tape stripping induced a mechanical disruption of the epidermal barrier that led to skin inflammation and subsequent emigration of LC and dermal DC from the skin. Emigrating LC and dermal DC were observed in lymphatic vessels, and the numbers of LC and dermal DC in the draining lymph node increased. Up to 500 times more injected precursors migrated into tape-stripped epidermis as compared with unstripped epidermis. Newly immigrated cells were slender with one or two dendrites and acquired a more dendritic morphology after 2-4 days. They were both MHC II-positive and negative and they did not express Langerin/CD207, nor macrophage-mannose receptor/CD206 and Fc-epsilon receptor I. In contrast, all cells that had entered the epidermis expressed CD11c and CCR6, suggesting that they were LC. We conclude that this experimental system may serve as a valuable tool for the further characterization of LC-precursors and the conditions necessary for LC-immigration into the epidermis.