title: Antigen-Specific IgG ameliorates allergic airway inflammation via Fcγ receptor IIB on dendritic cells.
abstract: BACKGROUND
  There have been few reports on the role of Fc receptors (FcRs) and immunoglobulin G (IgG) in asthma. The purpose of this study is to clarify the role of inhibitory FcRs and antigen presenting cells (APCs) in pathogenesis of asthma and to evaluate antigen-transporting and presenting capacity by APCs in the tracheobronchial mucosa.
  
  
  METHODS
  In FcγRIIB deficient (KO) and C57BL/6 (WT) mice, the effects of intratracheal instillation of antigen-specific IgG were analysed using the model with sensitization and airborne challenge with ovalbumin (OVA). Thoracic lymph nodes instilled with fluorescein-conjugated OVA were analysed by fluorescence microscopy. Moreover, we analysed the CD11c+ MHC class II+ cells which intaken fluorescein-conjugated OVA in thoracic lymph nodes by flow cytometry. Also, lung-derived CD11c+ APCs were analysed by flow cytometry. Effects of anti-OVA IgG1 on bone marrow dendritic cells (BMDCs) in vitro were also analysed. Moreover, in FcγRIIB KO mice intravenously transplanted dendritic cells (DCs) differentiated from BMDCs of WT mice, the effects of intratracheal instillation of anti-OVA IgG were evaluated by bronchoalveolar lavage (BAL).
  
  
  RESULTS
  In WT mice, total cells and eosinophils in BAL fluid reduced after instillation with anti-OVA IgG1. Anti-OVA IgG1 suppressed airway inflammation in hyperresponsiveness and histology. In addition, the number of the fluorescein-conjugated OVA in CD11c+ MHC class II+ cells of thoracic lymph nodes with anti-OVA IgG1 instillation decreased compared with PBS. Also, MHC class II expression on lung-derived CD11c+ APCs with anti-OVA IgG1 instillation reduced. Moreover, in vitro, we showed that BMDCs with anti-OVA IgG1 significantly decreased the T cell proliferation. Finally, we demonstrated that the lacking effects of anti-OVA IgG1 on airway inflammation on FcγRIIB KO mice were restored with WT-derived BMDCs transplanted intravenously.
  
  
  CONCLUSIONS
  Antigen-specific IgG ameliorates allergic airway inflammation via FcγRIIB on DCs.
authors.affiliation: Division of Respiratory Medicine, Department of Internal Medicine, Kobe University Graduate School of Medicine, Kobe, Japan.
authors.forename: Yumiko
authors.initials: Y
authors.lastname: Ishikawa
authors.forename: Kazuyuki
authors.initials: K
authors.lastname: Kobayashi
authors.forename: Masatsugu
authors.initials: M
authors.lastname: Yamamoto
authors.forename: Kyosuke
authors.initials: K
authors.lastname: Nakata
authors.forename: Tetsuya
authors.initials: T
authors.lastname: Takagawa
authors.forename: Yasuhiro
authors.initials: Y
authors.lastname: Funada
authors.forename: Yoshikazu
authors.initials: Y
authors.lastname: Kotani
authors.forename: Hajime
authors.initials: H
authors.lastname: Karasuyama
authors.forename: Masaru
authors.initials: M
authors.lastname: Yoshida
authors.forename: Yoshihiro
authors.initials: Y
authors.lastname: Nishimura
mesh_terms: D000818:Animals; D001249:Asthma / Q000235:genetics / Q000276:immunology / Q000503:physiopathology / Q000517:prevention & control*; D016535:Bronchial Hyperreactivity / Q000235:genetics / Q000276:immunology / Q000503:physiopathology / Q000517:prevention & control*; D001992:Bronchoalveolar Lavage Fluid / Q000166:cytology / Q000276:immunology; D039521:CD11c Antigen / Q000378:metabolism; D002478:Cells, Cultured; D003713:Dendritic Cells / Q000187:drug effects* / Q000276:immunology / Q000637:transplantation; D004195:Disease Models, Animal; D005260:Female; D005434:Flow Cytometry; D007074:Immunoglobulin G / Q000008:administration & dosage / Q000494:pharmacology*; D008198:Lymph Nodes / Q000187:drug effects / Q000276:immunology; D008213:Lymphocyte Activation / Q000187:drug effects; D051379:Mice; D008810:Mice, Inbred C57BL; D018345:Mice, Knockout; D008856:Microscopy, Fluorescence; D010047:Ovalbumin / Q000276:immunology*; D017452:Receptors, IgG / Q000172:deficiency / Q000235:genetics / Q000378:metabolism*; D018418:Th2 Cells / Q000187:drug effects / Q000276:immunology
chemical_list: D039521:CD11c Antigen; C499172:Fcgr2b protein, mouse; D007074:Immunoglobulin G; D017452:Receptors, IgG; D010047:Ovalbumin