title: Small airways response to naturalistic cat allergen exposure in subjects with asthma.
abstract: BACKGROUND
  It is currently unclear whether the small airways (diameter <2 microm) contribute significantly to late asthmatic reactions to inhaled allergen.
  
  
  OBJECTIVE
  We sought to determine whether naturalistic exposure to cat allergen induced late responses in the small airways as measured by pulmonary function testing and high-resolution computed tomography (HRCT) of the chest performed at end-expiration.
  
  
  METHODS
  In a group of 10 subjects with cat-induced asthma, physiologic studies (spirometry and lung volumes, including closing volume) and HRCT were performed before and 6 and 23 hours after a cat room challenge that caused a 20% or greater acute fall in FEV(1).
  
  
  RESULTS
  There was no significant decline in FEV(1) at 6 or 23 hours after cat exposure. Forced expiratory flow at 25% to 75% of forced vital capacity was significantly decreased at 6 hours after the challenge and returned to normal by 23 hours. HRCT image analysis as well as closing volume demonstrated increased air trapping from baseline at both 6 and 23 hours after the challenge. In addition, image analysis demonstrated a significant increase in small airways hyperresponsiveness to methacholine at 23 hours after the challenge. No significant mean changes were noted in lung volumes at either 6 or 23 hours or in PC(20) FEV(1) at 23 hours postchallenge.
  
  
  CONCLUSIONS
  These findings demonstrate that naturalistic exposure to cat allergen results in significant small airways obstruction and hyperresponsiveness persisting for at least 23 hours, at which time these changes cannot be detected by conventional physiologic measures.
  
  
  CONCLUSIONS
  Physiologically silent distal lung inflammation persists after an antigenic challenge.
authors.affiliation: Division of Pulmonary, David Geffen School of Medicine and Allergy Research Foundation, University of California, Los Angeles, CA 90025, USA.
authors.forename: Michelle R
authors.initials: MR
authors.lastname: Zeidler
authors.forename: Jonathan G
authors.initials: JG
authors.lastname: Goldin
authors.forename: Eric C
authors.initials: EC
authors.lastname: Kleerup
authors.forename: Hyun J
authors.initials: HJ
authors.lastname: Kim
authors.forename: Dao A
authors.initials: DA
authors.lastname: Truong
authors.forename: David W
authors.initials: DW
authors.lastname: Gjertson
authors.forename: Nola J
authors.initials: NJ
authors.lastname: Kennedy
authors.forename: Kenneth B
authors.initials: KB
authors.lastname: Newman
authors.forename: Donald P
authors.initials: DP
authors.lastname: Tashkin
authors.forename: Jeffrey M
authors.initials: JM
authors.lastname: Silverman
authors.forename: Jonathan
authors.initials: J
authors.lastname: Corren
mesh_terms: D000328:Adult; D000485:Allergens / Q000008:administration & dosage* / Q000276:immunology*; D000818:Animals; D001249:Asthma / Q000276:immunology* / Q000503:physiopathology*; D001985:Bronchial Provocation Tests; D001999:Bronchoscopy; D002000:Bronchospirometry; D002415:Cats; D005260:Female; D006023:Glycoproteins / Q000008:administration & dosage* / Q000276:immunology*; D006801:Humans; D008297:Male; D010991:Plethysmography; D014057:Tomography, X-Ray Computed; D014109:Total Lung Capacity
chemical_list: D000485:Allergens; D006023:Glycoproteins; C059296:Fel d 1 protein, Felis domesticus