title: Distribution of Langerhans cells and mast cells within the human oral mucosa: new application sites of allergens in sublingual immunotherapy?
abstract: BACKGROUND
  Sublingual immunotherapy (SLIT) represents an alternative to subcutaneous immunotherapy. While antigen-presenting cells such as Langerhans cells (LCs) are thought to contribute to the effectiveness of SLIT, mast cells (MCs) most likely account for adverse reactions such as sublingual edema. As little is known about LCs and MCs within the oral cavity, we investigated their distribution in search for mucosal sites with highest LCs and lowest MCs density.
  
  
  METHODS
  Biopsies were taken simultaneously from human vestibulum, bucca, palatum, lingua, sublingua, gingiva, and skin. Immunohistochemistry and flow cytometry were used to detect MCs, LCs and high affinity receptor for IgE (FcepsilonRI) expression of LCs. Mixed lymphocyte reactions were performed to assess their stimulatory capacity.
  
  
  RESULTS
  Highest density of MCs was detected within the gingiva, while the lowest density of MCs was found within the palatum and lingua. However, sublingual MCs were located within glands, which might explain swelling of sublingual caruncle in some SLIT patients. Highest density of LCs was detected within the vestibular region with lowest density in sublingual region. Highest expression of FcepsilonRI was detected on LCs within the vestibulum. Furthermore LCs from different regions displayed similar stimulatory capacity towards allogeneic T cells.
  
  
  CONCLUSIONS
  In view of our data, different mucosal regions such as the vestibulum might represent alternative SLIT application sites with potent allergen uptake. Our data might serve as a basis for new application strategies for SLIT to enhance efficiency and reduce local adverse reactions.
authors.affiliation: Department of Dermatology and Allergy, University of Bonn, Bonn, Germany.
authors.forename: J-P
authors.initials: JP
authors.lastname: Allam
authors.forename: G
authors.initials: G
authors.lastname: Stojanovski
authors.forename: N
authors.initials: N
authors.lastname: Friedrichs
authors.forename: W
authors.initials: W
authors.lastname: Peng
authors.forename: T
authors.initials: T
authors.lastname: Bieber
authors.forename: J
authors.initials: J
authors.lastname: Wenzel
authors.forename: N
authors.initials: N
authors.lastname: Novak
mesh_terms: D000286:Administration, Sublingual; D002452:Cell Count; D003888:Desensitization, Immunologic / Q000379:methods*; D006801:Humans; D006967:Hypersensitivity / Q000276:immunology* / Q000628:therapy; D007801:Langerhans Cells / Q000166:cytology / Q000276:immunology*; D008407:Mast Cells / Q000166:cytology / Q000276:immunology*; D009061:Mouth Mucosa / Q000166:cytology / Q000276:immunology*; D017455:Receptors, IgE / Q000276:immunology / Q000378:metabolism
chemical_list: D017455:Receptors, IgE