title: Peyer's patch dendritic cells sample antigens by extending dendrites through M cell-specific transcellular pores.
abstract: OBJECTIVE
  Peyer's patches (PPs) of the small intestine are antigen sampling and inductive sites that help establish mucosal immunity. Luminal antigens are transported from the mucosal surface of PPs to the subepithelial dome (SED), through the specialized epithelial M cells of the follicle-associated epithelium. Among the SED resident dendritic cells (DCs), which are situated ideally for taking up these antigens, some express high levels of lysozyme (LysoDC) and have strong phagocytic activity. We investigated the mechanisms by which LysoDCs capture luminal antigens in vivo.
  
  
  METHODS
  We performed 2-photon microscopy on explants of PPs from mice in which the enhanced green fluorescent protein gene was inserted into the lysozyme M locus (lys-EGFP mice), allowing fluorescence detection of LysoDC.
  
  
  RESULTS
  LysoDC extended dendrites through M-cell-specific transcellular pores to the gut lumen. The M-cell adhesion molecules junctional adhesion molecule-A and epithelial cell adhesion molecule were recruited to sites of transcellular migration. Transcellular dendrites scanned the M-cell apical surface and the gut luminal content; they were able to take pathogenic bacteria and inert particles in the lumen before retracting back to the SED.
  
  
  CONCLUSIONS
  We describe an antigen sampling mechanism that occurs in PPs and involves cooperation between M cells of the follicle-associated epithelium and DCs of the subepithelial dome. This process might be developed to target vaccines to the mucosa.
authors.affiliation: Aix-Marseille University, Centre d'Immunologie de Marseille-Luminy, Marseille, France.
authors.forename: Hugues
authors.initials: H
authors.lastname: Lelouard
authors.forename: Mathieu
authors.initials: M
authors.lastname: Fallet
authors.forename: Béatrice
authors.initials: B
authors.lastname: de Bovis
authors.forename: Stéphane
authors.initials: S
authors.lastname: Méresse
authors.forename: Jean-Pierre
authors.initials: JP
authors.lastname: Gorvel
mesh_terms: D000818:Animals; D000941:Antigens / Q000276:immunology*; D000951:Antigens, Neoplasm / Q000378:metabolism; D015815:Cell Adhesion Molecules / Q000378:metabolism; D002450:Cell Communication; D002465:Cell Movement; D003713:Dendritic Cells / Q000276:immunology* / Q000382:microbiology; D004195:Disease Models, Animal; D000071858:Epithelial Cell Adhesion Molecule; D005455:Fluorescent Antibody Technique; D049452:Green Fluorescent Proteins / Q000096:biosynthesis / Q000235:genetics; D018928:Immunity, Mucosal; D007413:Intestinal Mucosa / Q000276:immunology* / Q000382:microbiology; D051379:Mice; D008807:Mice, Inbred BALB C; D008810:Mice, Inbred C57BL; D008822:Mice, Transgenic; D018613:Microscopy, Confocal; D009113:Muramidase / Q000235:genetics; D010539:Permeability; D010581:Peyer's Patches / Q000276:immunology* / Q000382:microbiology; D011956:Receptors, Cell Surface / Q000378:metabolism; D012480:Salmonella Infections / Q000276:immunology* / Q000382:microbiology; D012486:Salmonella typhimurium / Q000276:immunology / Q000472:pathogenicity; D013997:Time Factors
chemical_list: D000941:Antigens; D000951:Antigens, Neoplasm; D015815:Cell Adhesion Molecules; D000071858:Epithelial Cell Adhesion Molecule; C498686:F11r protein, mouse; D011956:Receptors, Cell Surface; C485184:enhanced green fluorescent protein; D049452:Green Fluorescent Proteins; D009113:Muramidase; C472450:lysozyme M, mouse