title: Breakdown of mucosal immunity in gut by 2,3,7,8-tetraclorodibenzo-p-dioxin (TCDD).
abstract: OBJECTIVE
  Mucosal immunity plays a pivotal role for body defense against infection and allergy. The aim of this study was to clarify the effects of 2,3,7,8-tetraclorodibenzo-p-dioxin (TCDD) on mucosal immunity in the gut.
  
  
  METHODS
  Fecal IgA level and oral tolerance induction were examined in TCDD-treated mice. Flow cytometric and histological analyses were also performed.
  
  
  RESULTS
  Single oral administration of low dose 2,3,7,8-TCDD resulted in a marked decrease in IgA secretion in the gut without any effects on the cellular components of gut-associated lymphoid tissues (GALT) including Peyer's patches (PPs) and mesenteric lymph nodes (LNs). Decressed IgA secretion by TCDD was not observed in aryl hydrocarbon receptor (AhR)-deficient mice. Flow cytometric analysis revealed that IgA B cells in PPs and the mesenteric LNs remained unchanged in the TCDD-treated mice. An immunofluorescence study also demonstrated that a significant number of cytoplasmic IgA cells were present in the lamina propria of the gut in the TCDD-treated mice. Furthermore, oral tolerance induction by ovalbumin (OVA) was impaired in the TCDD-treated mice and OVA-specific T cell proliferation occurred in the peripheral lymphoid tissues including the spleen and LNs.
  
  
  CONCLUSIONS
  These results suggest that a relatively low dose of TCDD impairs mucosal immunity in the gut and induces systemic sensitization by oral antigens.
authors: Department of Molecular Preventive Medicine, School of Medicine, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, 113-0033, Tokyo, Japan.
authors: Hirokazu
authors: H
authors: Kinoshita
authors: Jun
authors: J
authors: Abe
authors: Kenji
authors: K
authors: Akadegawa
authors: Hideaki
authors: H
authors: Yurino
authors: Tetsuya
authors: T
authors: Uchida
authors: Shigaku
authors: S
authors: Ikeda
authors: Kouji
authors: K
authors: Matsushima
authors: Sho
authors: S
authors: Ishikawa