title: Langerhans cells: mediators of immunity and tolerance.
abstract: Langerhans cells provide the epidermis with a surveillance network that samples the external environment influencing the decision between immunity and tolerance. Langerhans cells are immature dendritic cells acquiring antigens from foreign invaders as well as damaged native tissue for display to the immune response. The current paradigm suggests that the state of maturity of Langerhans cells, defined by the display of molecules that provoke immune responses (histocompatibility, co-stimulators, adhesion and homing receptors), determines whether emigration of the Langerhans cell to lymph nodes signals immunity or tolerance. Other factors such as type of immunogen ingested, environmental danger signals and the level of cell death may also play a role in tipping the balance towards immunity or immunosuppression. As modulators of the immune response, Langerhans cells play a role in cutaneous autoimmunity in lupus and in cancers that have an affinity for the epidermis such as cutaneous T cell lymphoma.
authors.affiliation: Yale University, School of Medicine, Department of Dermatology and Comprehensive Cancer Center, New Haven, CT 06520, USA. carole.berger@yale.edu
authors.forename: Carole L
authors.initials: CL
authors.lastname: Berger
authors.forename: Juan Gabriel
authors.initials: JG
authors.lastname: Vasquez
authors.forename: Joshua
authors.initials: J
authors.lastname: Shofner
authors.forename: Kavita
authors.initials: K
authors.lastname: Mariwalla
authors.forename: Richard L
authors.initials: RL
authors.lastname: Edelson
mesh_terms: D000818:Animals; D003713:Dendritic Cells / Q000166:cytology / Q000276:immunology* / Q000473:pathology; D000078404:Epidermal Cells; D004817:Epidermis / Q000276:immunology* / Q000473:pathology; D006801:Humans; D007108:Immune Tolerance; D007801:Langerhans Cells / Q000166:cytology / Q000276:immunology* / Q000473:pathology; D012871:Skin Diseases / Q000276:immunology / Q000473:pathology*