title: Prior airway exposure to allergen increases virus-induced airway hyperresponsiveness.
abstract: BACKGROUND
  Respiratory syncytial virus (RSV) bronchiolitis in early life can lead to changes in airway function, but there are likely additional predisposing factors, such as prior allergen exposure, determining which children develop wheezing and asthma.
  
  
  OBJECTIVE
  To define the effects of prior airway exposure to sensitizing allergen on the development of airway inflammation and hyperresponsiveness (AHR) to subsequent RSV infection.
  
  
  METHODS
  BALB/c mice were exposed to ovalbumin or PBS exclusively through the airways and subsequently infected with RSV or sham-inoculated. AHR, lung inflammation, and the frequency of cytokine-producing T lymphocytes in the lung were determined.
  
  
  RESULTS
  In PBS-exposed mice, RSV infection induced AHR and an increased proportion of TH1-type (IFN-gamma and IL-12) cytokine-producing cells in the lungs. However, in mice previously exposed to ovalbumin through the airways and subsequently infected with RSV, the degree of AHR was significantly increased and was associated with an increased proportion of TH2 (IL-4, IL-5) cytokine-producing T lymphocytes. This response was also associated with an increased accumulation of eosinophils, neutrophils, and CD8+ T cells in the lungs.
  
  
  CONCLUSIONS
  These data suggest that prior airway exposure to allergen may predispose sensitized hosts to a greater degree of altered airway function upon subsequent respiratory viral infection.
authors: Department of Pediatrics, National Jewish Medical and Research Center, Denver, Colo 80206, USA.
authors: Mika J
authors: MJ
authors: Mäkelä
authors: Ralph
authors: R
authors: Tripp
authors: Azzeddine
authors: A
authors: Dakhama
authors: Jun-Won
authors: JW
authors: Park
authors: Toshihide
authors: T
authors: Ikemura
authors: Anthony
authors: A
authors: Joetham
authors: Matti
authors: M
authors: Waris
authors: Larry J
authors: LJ
authors: Anderson
authors: Erwin W
authors: EW
authors: Gelfand
mesh_terms: D000280:Administration, Inhalation; D000818:Animals; D016535:Bronchial Hyperreactivity / Q000503:physiopathology* / Q000821:virology*; D016207:Cytokines / Q000096:biosynthesis; D005260:Female; D008168:Lung / Q000378:metabolism / Q000473:pathology; D008214:Lymphocytes / Q000378:metabolism / Q000473:pathology; D051379:Mice; D008807:Mice, Inbred BALB C; D010047:Ovalbumin / Q000008:administration & dosage / Q000276:immunology*; D011024:Pneumonia, Viral / Q000209:etiology / Q000473:pathology; D018357:Respiratory Syncytial Virus Infections / Q000150:complications* / Q000473:pathology; D012137:Respiratory System / Q000276:immunology*
chemical_list: D016207:Cytokines; D010047:Ovalbumin