title: Sputum and bronchial submucosal IL-13 expression in asthma and eosinophilic bronchitis.
abstract: BACKGROUND
  Nonasthmatic eosinophilic bronchitis is a condition characterized by the presence of eosinophilic airway inflammation in the absence of airflow obstruction or airway hyperresponsiveness. In asthma, the T H 2-type cytokine IL-13 has been implicated in the development of airway inflammation and hyperresponsiveness. Whether the expression of IL-13 is different between these 2 conditions is unknown.
  
  
  OBJECTIVE
  We sought to investigate whether IL-13 expression is increased in asthma compared with eosinophilic bronchitis.
  
  
  METHODS
  Sputum samples from subjects with mild asthma (n = 30) and eosinophilic bronchitis (n = 15) and normal controls (n = 16) were dialyzed, and IL-13 concentration was measured by ELISA. In a subgroup of these patients, IL-13 protein expression in bronchial biopsies was assessed by immunohistochemistry.
  
  
  RESULTS
  The concentration of sputum IL-13 was higher in patients with mild asthma than in normal controls ( P = .03) and in patients with eosinophilic bronchitis ( P = .03). The median (interquartile range) number of IL-13 + cells/mm 2 submucosa was significantly higher in asthma 4 (8) than eosinophilic bronchitis 1.7 (1.9) and normal controls 0.5 (1.1; P = .004). Eighty-three percent of the cells expressing IL-13 in the submucosa were eosinophils, and 8% were mast cells. The median (interquartile range) proportion of eosinophils that expressed IL-13 was higher in the subjects with asthma, 16 (10)%, than those with eosinophilic bronchitis, 7 (3)% ( P = .02).
  
  
  CONCLUSIONS
  The increased expression of IL-13 in asthma compared with eosinophilic bronchitis supports the concept that IL-13 may play a critical role in the pathophysiology of asthma.
authors.affiliation: Institute for Lung Health, University Hospitals of Leicester, Groby Road, Leicester LE3 9QP, UK.
authors.forename: Mike A
authors.initials: MA
authors.lastname: Berry
authors.forename: Deborah
authors.initials: D
authors.lastname: Parker
authors.forename: Natalie
authors.initials: N
authors.lastname: Neale
authors.forename: Lucy
authors.initials: L
authors.lastname: Woodman
authors.forename: Angela
authors.initials: A
authors.lastname: Morgan
authors.forename: Phillip
authors.initials: P
authors.lastname: Monk
authors.forename: Peter
authors.initials: P
authors.lastname: Bradding
authors.forename: Andrew J
authors.initials: AJ
authors.lastname: Wardlaw
authors.forename: Ian D
authors.initials: ID
authors.lastname: Pavord
authors.forename: Christopher E
authors.initials: CE
authors.lastname: Brightling
mesh_terms: D000328:Adult; D000368:Aged; D001249:Asthma / Q000276:immunology*; D001980:Bronchi / Q000737:chemistry*; D001991:Bronchitis / Q000276:immunology*; D004797:Enzyme-Linked Immunosorbent Assay; D004802:Eosinophilia / Q000276:immunology*; D005260:Female; D006801:Humans; D018793:Interleukin-13 / Q000032:analysis*; D008297:Male; D008875:Middle Aged; D020545:Respiratory Mucosa / Q000737:chemistry; D013183:Sputum / Q000737:chemistry*
chemical_list: D018793:Interleukin-13