title: Fc-epsilon-RI, the high affinity IgE-receptor, is robustly expressed in the upper gastrointestinal tract and modulated by mucosal inflammation.
abstract: BACKGROUND
  The role of the high affinity IgE receptor, FcεRI, in IgE-mediated immune responses of the gastrointestinal (GI) mucosa is poorly understood. Currently, a detailed characterization of FcεRI expression throughout the human gut is lacking. The aim of this study was to define the expression pattern of FcεRI in the GI tract.
  
  
  RESULTS
  We compared FcεRI expression in children with gastritis/esophagitis (n = 10), celiac disease (n = 10), inflammatory bowel disease (IBD) (n = 9), and normal mucosa (n = 5). The α-subunit of FcεRI (FcεRIα), detected by immunohistochemistry, was found on cells infiltrating the mucosa of the esophagus, the stomach, and the duodenum, but was rarely detected in more distal sections of the GI tract. Accordingly, quantitative RT-PCR analysis on esophagus, stomach, duodenum, colon, and rectum biopsies revealed that FcεRIα and -β expression levels decreased towards the distal intestine. mRNA transcripts of the common Fc-receptor-γ chain were present in the entire GI mucosa. Double-immunofluorescence staining of esophageal specimens confirmed that FcεRIα was expressed on intraepithelial mast cells and Langerhans cells. The mRNA expression levels of the α, β, and γ subunits of FcεRI did not correlate with total serum IgE but were associated with mucosal inflammation.
  
  
  CONCLUSIONS
  Our data define the upper GI tract as the main site for IgE-mediated immune activation via FcεRI. Tissue mRNA levels of FcεRIα are regulated by inflammatory conditions rather than serum IgE, indicating that FcεRI might also play a role in pathologies other than allergy.
authors: Department of Paediatrics and Adolescent Medicine, Medical University of Vienna, Vienna, Austria.
authors: Christina
authors: C
authors: Bannert
authors: Bettina
authors: B
authors: Bidmon-Fliegenschnee
authors: Georg
authors: G
authors: Stary
authors: Florian
authors: F
authors: Hotzy
authors: Judith
authors: J
authors: Stift
authors: Samuel
authors: S
authors: Nurko
authors: Zsolt
authors: Z
authors: Szépfalusi
authors: Edda
authors: E
authors: Fiebiger
authors: Eleonora
authors: E
authors: Dehlink
mesh_terms: D000293:Adolescent; D002648:Child; D002675:Child, Preschool; D005260:Female; D005786:Gene Expression Regulation; D006801:Humans; D007073:Immunoglobulin E / Q000097:blood; D007249:Inflammation / Q000235:genetics / Q000378:metabolism; D008297:Male; D009092:Mucous Membrane / Q000378:metabolism; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism; D017455:Receptors, IgE / Q000235:genetics*; D041742:Upper Gastrointestinal Tract / Q000378:metabolism*
chemical_list: D012333:RNA, Messenger; D017455:Receptors, IgE; D007073:Immunoglobulin E