Skin DCs go deeper

Skin dendritic cells (DCs), called Langerhans cells (LCs), reside in the epidermis, where they express a lectin called langerin. Although DCs were also known to reside in the dermis, these cells were not thought to express langerin. But three reports by Bursch et al. (page 3147), Poulin et al. (page 3119), and Ginhoux et al. (page 3133) now show that a subset of langerin-expressing DCs call the dermis home.

The new cells were discovered in mice whose own bone marrow had been eliminated by irradiation and replaced with donor bone marrow. The irradiation eliminates all immune cells except for epidermal LCs. Six weeks after bone marrow transplant, Bursch et al. found that epidermal LCs were primarily from the host, as expected. But they also found donor-derived DCs that expressed langerin...