title: Indoleamine 2,3-dioxygenase-expressing myeloid dendritic cells and macrophages in infectious and noninfectious cutaneous granulomas.
abstract: BACKGROUND
  The enzyme indoleamine 2,3-dioxygenase (IDO) degrades the essential amino acid tryptophan, and this degradation is an immunosuppressive mechanism that is mainly used by antigen-presenting cells. IDO-expressing dendritic cells and macrophages have previously been identified as components of lymph node granulomas after Listeria monocytogenes infection. In this study we undertook an analysis of IDO expression in granulomas of infectious and noninfectious origin in the human skin.
  
  
  METHODS
  Lesional skin biopsy specimens (n = 22) from different granulomatous skin disorders (lupus vulgaris, sarcoidosis, granuloma annulare, leprosy) were analyzed. Immunohistochemistry was performed to identify and locate the enzyme IDO within the inflammatory granulomatous infiltrate (IDO, CD11c, CD68, S100, CD3, Foxp3). Two-color immunofluorescence of IDO in combination with multiple markers was applied to characterize the IDO-expressing cells.
  
  
  RESULTS
  Cutaneous granulomas of different origin strongly express IDO, mainly in the center and in the ring wall of the granulomas. We demonstrate that in infectious, but also in noninfectious human cutaneous granulomas the large myeloid CD11c(+)S100(+)CD68(-) dendritic cells and the CD68(+) macrophages express IDO.
  
  
  CONCLUSIONS
  This study was limited by the lack of details about the exact stage or maturity of granuloma formation in the specimens investigated.
  
  
  CONCLUSIONS
  These findings reveal that IDO expression in myeloid dendritic cells and macrophages is part of an integrated response of granuloma formation, which may be a unifying feature of granulomatous reactions in the skin.
authors.affiliation: Department of Dermatology, Friedrich-Wilhelms-University, Bonn, Germany. Electronic address: d.bubnoff@uni-bonn.de.
authors.forename: Dagmar
authors.initials: D
authors.lastname: von Bubnoff
authors.affiliation: Department of Dermatology, Friedrich-Wilhelms-University, Bonn, Germany.
authors.forename: Marina
authors.initials: M
authors.lastname: Scheler
authors.affiliation: Department of Dermatology, Friedrich-Wilhelms-University, Bonn, Germany.
authors.forename: Helene
authors.initials: H
authors.lastname: Wilms
authors.affiliation: Department of Dermatology, Friedrich-Wilhelms-University, Bonn, Germany.
authors.forename: Jörg
authors.initials: J
authors.lastname: Wenzel
authors.affiliation: III Medizinische Klinik, Klinikum Rechts der Isar, Technische Universität München, München, Germany.
authors.forename: Nikolas
authors.initials: N
authors.lastname: von Bubnoff
authors.affiliation: Institute of Medical Microbiology and Hygiene, University of Freiburg, Freiburg, Germany.
authors.forename: Georg
authors.initials: G
authors.lastname: Häcker
authors.affiliation: Institute for Life and Medical Sciences Bonn, Friedrich-Wilhelms-University, Bonn, Germany.
authors.forename: Joachim
authors.initials: J
authors.lastname: Schultze
authors.affiliation: Institute for Life and Medical Sciences Bonn, Friedrich-Wilhelms-University, Bonn, Germany.
authors.forename: Alexey
authors.initials: A
authors.lastname: Popov
authors.affiliation: Bernhard Nocht Institute for Tropical Medicine, Hamburg, Germany.
authors.forename: Paul
authors.initials: P
authors.lastname: Racz
authors.affiliation: Department of Dermatology, Friedrich-Wilhelms-University, Bonn, Germany.
authors.forename: Thomas
authors.initials: T
authors.lastname: Bieber
authors.affiliation: Institute of Pathology, University of Leipzig, Leipzig, Germany.
authors.forename: Claudia
authors.initials: C
authors.lastname: Wickenhauser
mesh_terms: D003713:Dendritic Cells / Q000201:enzymology*; D006099:Granuloma / Q000201:enzymology* / Q000473:pathology; D006801:Humans; D007150:Immunohistochemistry; D050503:Indoleamine-Pyrrole 2,3,-Dioxygenase / Q000096:biosynthesis*; D008264:Macrophages / Q000201:enzymology*; D022423:Myeloid Cells / Q000201:enzymology*; D012867:Skin / Q000378:metabolism
chemical_list: D050503:Indoleamine-Pyrrole 2,3,-Dioxygenase