title: Intraepithelial lymphocyte eotaxin-2 expression and perineural mast cell degranulation differentiate allergic/eosinophilic colitis from classic IBD.
abstract: OBJECTIVE
  Allergic colitis shows overlap with classic inflammatory bowel disease (IBD). Clinically, allergic colitis is associated with dysmotility and abdominal pain, and mucosal eosinophilia is characteristic. We thus aimed to characterise mucosal changes in children with allergic colitis compared with normal tissue and classic IBD, focusing on potential interaction between eosinophils and mast cells with enteric neurones.
  
  
  METHODS
  A total of 15 children with allergic colitis, 10 with Crohn disease (CD), 10 with ulcerative colitis (UC), and 10 histologically normal controls were studied. Mucosal biopsies were stained for CD3 T cells, Ki-67, eotaxin-1, and eotaxin-2. Eotaxin-2, IgE, and tryptase were localised compared with mucosal nerves, using neuronal markers neurofilament protein, neuron-specific enolase, and nerve growth factor receptor.
  
  
  RESULTS
  Overall inflammation was greater in patients with CD and UC than in patients with allergic colitis. CD3 T-cell density was increased in patients with allergic colitis, similar to that in patients with CD but lower than in patients with UC, whereas eosinophil density was higher than in all other groups. Eotaxin-1 and -2 were localised to basolateral crypt epithelium in all specimens, with eotaxin-1+ lamina propria cells found in all of the colitis groups. Eotaxin-2+ intraepithelial lymphocyte (IEL) density was significantly higher in allergic colitis specimens than in all other groups. Mast cell degranulation was strikingly increased in patients with allergic colitis (12/15) compared with that in patients with UC (1/10) and CD (0/1). Tryptase and IgE colocalised on enteric neurons in patients with allergic colitis but rarely in patients with IBD.
  
  
  CONCLUSIONS
  Eotaxin-2+ IELs may contribute to the periepithelial eosinophil accumulation characteristic of allergic colitis. The colocalisation of IgE and tryptase with mucosal enteric nerves is likely to promote the dysmotility and visceral hyperalgesia classically seen in allergic gastrointestinal inflammation.
authors.affiliation: *Department of Paediatric Gastroenterology, Addenbrooke's Hospital, Cambridge, UK †Department of Paediatric Gastroenterology, Gaslini Institute, Genoa, Italy ‡Division of Metabolic and Vascular, Warwick Medical School, University of Warwick, Warwick, UK.
authors.forename: Franco
authors.initials: F
authors.lastname: Torrente
authors.forename: Arrigo
authors.initials: A
authors.lastname: Barabino
authors.forename: Tommaso
authors.initials: T
authors.lastname: Bellini
authors.forename: Simon H
authors.initials: SH
authors.lastname: Murch
mesh_terms: D000293:Adolescent; D017252:CD3 Complex / Q000032:analysis; D015550:Cell Degranulation; D054413:Chemokine CCL11 / Q000032:analysis; D054423:Chemokine CCL24 / Q000032:analysis*; D002648:Child; D002675:Child, Preschool; D003092:Colitis / Q000276:immunology / Q000473:pathology*; D003093:Colitis, Ulcerative / Q000473:pathology; D003424:Crohn Disease / Q000473:pathology; D017615:Enteric Nervous System / Q000737:chemistry; D004802:Eosinophilia / Q000276:immunology / Q000473:pathology*; D004848:Epithelium / Q000737:chemistry; D005260:Female; D005512:Food Hypersensitivity / Q000473:pathology*; D006801:Humans; D007073:Immunoglobulin E / Q000032:analysis; D007223:Infant; D007413:Intestinal Mucosa / Q000737:chemistry / Q000473:pathology; D019394:Ki-67 Antigen / Q000032:analysis; D018655:Lymphocyte Count; D008297:Male; D008407:Mast Cells / Q000502:physiology*; D009474:Neurons / Q000737:chemistry; D013601:T-Lymphocytes / Q000737:chemistry*; D053802:Tryptases / Q000032:analysis
chemical_list: C515456:CCL11 protein, human; C515484:CCL24 protein, human; D017252:CD3 Complex; D054413:Chemokine CCL11; D054423:Chemokine CCL24; D019394:Ki-67 Antigen; D007073:Immunoglobulin E; D053802:Tryptases