title: Bronchial allergen challenge using the Medicaid dosimeter.
abstract: BACKGROUND
  Bronchial allergen provocations are well established in asthma research. We evaluated the reproducibility of single-concentration, single-step allergen challenges in volunteers with grass pollen allergy.
  
  
  METHODS
  Forty-seven subjects underwent bronchial challenges using the aerosol provocation system nebulizer (Medicaid Sidestream) with incremental doses of grass pollen to define the individual allergen dose that causes a 20% drop in FEV(1) (PD(20)FEV(1)). In 39 subjects this procedure was followed by single-step challenges. Early and late asthmatic responses were monitored, and increases in exhaled nitric oxide were measured before and 24 h after single-step challenges.
  
  
  RESULTS
  After the first single-step challenge, the maximum drop in FEV(1) was 21.3% ± 8.0. A comparison of the drop in FEV(1) to the initial incremental challenge (29.7% ± 7.5) revealed an intraclass correlation of -0.30 (p < 0.05). In the second single-step challenge, the mean drop in FEV(1) was 20.9% ± 7.2. Compared with the first single-step challenge, the intraclass correlation was 0.37 (p < 0.05) and the 95% limits of agreement according to Bland and Altman were -17.5 to 18.1%. The increases in exhaled nitric oxide revealed substantial agreement in repeated single-step challenges (26.8 ppb ± 27.8 and 21.8 ppb ± 21.9, ICC 0.62, p < 0.001).
  
  
  CONCLUSIONS
  The use of aerosol provocation system to calculate the PD(20)FEV(1) allergen is a timesaving procedure and is less prone to errors because only one dilution of the allergen is used. The repeatability in well-defined subjects is excellent to study the mechanisms of allergen-induced airway inflammation and the development of new treatments for allergic diseases.
authors.affiliation: Department of Allergy, Pulmonology and Cystic Fibrosis, Children's Hospital, Goethe-University, Theodor Stern Kai 7, Frankfurt am Main, Germany. Johannes.Schulze@kgu.de
authors.forename: Johannes
authors.initials: J
authors.lastname: Schulze
authors.forename: Martin
authors.initials: M
authors.lastname: Rosewich
authors.forename: Melanie
authors.initials: M
authors.lastname: Dressler
authors.forename: Carsten
authors.initials: C
authors.lastname: Riemer
authors.forename: Markus A
authors.initials: MA
authors.lastname: Rose
authors.forename: Stefan
authors.initials: S
authors.lastname: Zielen
mesh_terms: D000293:Adolescent; D000328:Adult; D000485:Allergens / Q000276:immunology; D001249:Asthma / Q000276:immunology / Q000628:therapy; D001985:Bronchial Provocation Tests / Q000009:adverse effects / Q000295:instrumentation* / Q000379:methods; D005260:Female; D006801:Humans; D008297:Male; D036501:Metered Dose Inhalers; D006109:Poaceae / Q000276:immunology; D011058:Pollen / Q000276:immunology; D015203:Reproducibility of Results; D012882:Skin Tests; D055815:Young Adult
chemical_list: D000485:Allergens