Identification of TROP2 (TACSTD2), an EpCAM-like molecule, as a specific marker for TGF-Β1-dependent human epidermal langerhans cells

Abstract

Langerin (CD207) expression is a hallmark of epidermal Langerhans cells (LCs); however, CD207 cells comprise several functional subsets. Murine studies showed that epidermal, but not dermal, CD207 cells require transforming growth factor-Β 1 (TGF-Β1) for development, whereas human data are lacking. Using gene profiling, we found that the surface molecule TROP2 (TACSTD2) is strongly and rapidly induced during TGF-Β1-dependent LC commitment of human CD34+ hematopoietic progenitor cells or monocytes. TROP2 is conserved between mouse and human, and shares substantial amino-acid identity with EpCAM, a marker for murine epidermal LCs. To our knowledge, neither TROP2 nor EpCAM expression has been analyzed in human dendritic cell (DC) subsets. We found that (i) all human epidermal LCs are TROP2 EpCAM ; (ii) human dermis lacks CD207 EpCAM or CD207 TROP2 DCs, i.e., equivalents of murine dermal CD207 DCs; and (iii) pulmonary CD207 cells are TROP2 EpCAM . Moreover, although EpCAM was broadly expressed by pulmonary and intestinal epithelial cells, as well as by bone marrow erythroid progenitor cells, these cells lacked TROP2. However, although TROP2 is expressed by human LCs as well as by human and murine keratinocytes, most murine LCs, except of a small subset, lacked TROP2. Therefore, TROP2 is a marker for human TGF-Β1-dependent epidermal LCs. © 2011 The Society for Investigative Dermatology.