title: The corneal stroma is endowed with a significant number of resident dendritic cells.
abstract: OBJECTIVE
  Dendritic cells (DCs) comprise a system of highly efficient antigen-presenting cells (APCs) that initiate immune responses. The purpose of this study was to examine the normal stroma for the presence of DCs and other bone marrow (BM)-derived cells.
  
  
  METHODS
  Normal uninflamed corneas of BALB/c and other murine strains were excised, and immunofluorescence single- and double-staining for multiple markers was performed for examination by confocal microscopy. Corneal buttons were placed in culture and immunocytochemistry and flow cytometry performed.
  
  
  RESULTS
  MHC class II(+)CD80(+)CD86(+) cells were found in the periphery of the anterior normal stroma. These cells were CD45(+), CD11c(+)CD11b(+) suggesting a BM-derived and monocytic DC lineage. In a surprising finding, significant numbers of MHC class II(-)CD80(-)CD86(-) cells were found in the center of the anterior stroma. These cells were also CD45(+)CD11c(+)CD11b(+) but CD3(-), GR-1(-), keratan sulfate(-), and CD8alpha(-), reflecting an immature precursor phenotype of myeloid DC. In addition to DC subsets in the anterior stroma, a CD11c(-)CD11b(+) population of BM-derived cells was found primarily in the posterior stroma, representing monocytes/macrophages. These cells were rarely present in the anterior third of the normal stroma. Further, CD14(+) precursor-type DCs were found throughout the stroma. These in vivo findings were not strain specific and were confirmed by immunocytochemistry and flow cytometry analyses of cells derived from corneal explants and by transmission electron microscopy.
  
  
  CONCLUSIONS
  This study demonstrates that, in addition to the known Langerhans cells in the corneal epithelium, at least three BM-derived cell subsets reside in the normal corneal stroma.
authors.affiliation: Laboratory of Immunology, Schepens Eye Research Institute, and the Department of Ophthalmology and Massachusetts Eye and Ear Infirmary, Harvard Medical School, Boston, Massachusetts 02114, USA.
authors.forename: Pedram
authors.initials: P
authors.lastname: Hamrah
authors.forename: Ying
authors.initials: Y
authors.lastname: Liu
authors.forename: Qiang
authors.initials: Q
authors.lastname: Zhang
authors.forename: M Reza
authors.initials: MR
authors.lastname: Dana
mesh_terms: D000818:Animals; D015703:Antigens, CD / Q000378:metabolism; D002478:Cells, Cultured; D003319:Corneal Stroma / Q000166:cytology*; D003713:Dendritic Cells / Q000166:cytology* / Q000378:metabolism / Q000648:ultrastructure; D005434:Flow Cytometry; D019084:Fluorescent Antibody Technique, Indirect; D000949:Histocompatibility Antigens Class II / Q000378:metabolism; D016130:Immunophenotyping; D008297:Male; D051379:Mice; D008807:Mice, Inbred BALB C; D008809:Mice, Inbred C3H; D008810:Mice, Inbred C57BL; D018613:Microscopy, Confocal
chemical_list: D015703:Antigens, CD; D000949:Histocompatibility Antigens Class II