title: Human epidermal Langerhans cells maintain immune homeostasis in skin by activating skin resident regulatory T cells.
abstract: Recent studies have demonstrated that the skin of a normal adult human contains 10-20 billion resident memory T cells, including various helper, cytotoxic, and regulatory T cell subsets, that are poised to respond to environmental antigens. Using only autologous human tissues, we report that both in vitro and in vivo, resting epidermal Langerhan cells (LCs) selectively and specifically induced the activation and proliferation of skin resident regulatory T (Treg) cells, a minor subset of skin resident memory T cells. In the presence of foreign pathogen, however, the same LCs activated and induced proliferation of effector memory T (Tem) cells and limited Treg cells' activation. These underappreciated properties of LCs, namely maintenance of tolerance in normal skin, and activation of protective skin resident memory T cells upon infectious challenge, help clarify the role of LCs in skin.
authors.affiliation: Department of Dermatology/Harvard Skin Disease Research Center, Brigham and Women's Hospital, Boston, MA 02115, USA.
authors.forename: Julien
authors.initials: J
authors.lastname: Seneschal
authors.forename: Rachael A
authors.initials: RA
authors.lastname: Clark
authors.forename: Ahmed
authors.initials: A
authors.lastname: Gehad
authors.forename: Clare M
authors.initials: CM
authors.lastname: Baecher-Allan
authors.forename: Thomas S
authors.initials: TS
authors.lastname: Kupper
mesh_terms: D000941:Antigens / Q000276:immunology; D048708:Cell Growth Processes / Q000276:immunology; D004817:Epidermis / Q000276:immunology*; D006706:Homeostasis / Q000276:immunology; D006801:Humans; D007156:Immunologic Memory / Q000276:immunology; D007801:Langerhans Cells / Q000276:immunology*; D008213:Lymphocyte Activation / Q000276:immunology; D012867:Skin / Q000166:cytology / Q000276:immunology*; D050378:T-Lymphocytes, Regulatory / Q000276:immunology*
chemical_list: D000941:Antigens