title: Relationship of allergic degree and PC20 level in adults with positive methacholine challenge test.
abstract: BACKGROUND
  The relationship between allergic markers and PC(20) (provocative concentration causing a 20% fall in FEV(1)) in adults with positive methacholine challenge test (MCT) is still subject to discussion.
  
  
  OBJECTIVE
  The goal of this study is to determine whether the degree of bronchial hyperresponsiveness (BHR) is correlated with the severity of atopy or not.
  
  
  METHODS
  Forty patients with persistent cough and/or unexplained episodes of dyspnea exhibiting a normal baseline pulmonary function test and positive MCT were enrolled in this study. They were divided into two groups according to their Phadiatop response (positive and negative), and three groups by PC(20) level: PC(20) < 1.25 mg/ml, 1.25 mg/ml < or = PC(20) < 5 mg/ml, and 5 mg/ml < or = PC(20) < 25 mg/ml.
  
  
  RESULTS
  Twenty-three patients (57.5%) were Phadiatop positive. Of the 23 Phadiatop-positive patients, 20 patients (87%) were positive for specific serum IgE to Dermatophagoides pteronyssinus (D1) and Dermatophagoides farinae (D2). The total serum IgE and eosinophil cationic protein (ECP) level of the Phadiatop-positive group were higher than those of the Phadiatop-negative group (p < 0.0001 and p = 0.005, respectively). The age, gender, FEV(1)/FVC ratio, ECP and total serum IgE level were not significantly different in the three PC(20) subgroups. The Phadiatop response and PC(20) level were significantly correlated (p = 0.0063). For Phadiatop-positive adults, PC(20) level was not significantly correlated with total serum IgE and specific serum IgE to D1 and D2.
  
  
  CONCLUSIONS
  Atopy is related to adults with positive MCT. However, the degree of BHR to methacholine is not significantly correlated with the severity of atopy.
authors.affiliation: Division of Pulmonary and Critical Care Medicine, Department of Internal Medicine, Kaohsiung Chang Gung Memorial Hospital, Kaohsiung, 123 Ta-Pei Road, Niao-Sung Hsiang, Kaohsiung Hsien, Taiwan, ROC.
authors.forename: Shih-Feng
authors.initials: SF
authors.lastname: Liu
authors.forename: Meng-Chih
authors.initials: MC
authors.lastname: Lin
authors.forename: Hsueh-Wen
authors.initials: HW
authors.lastname: Chang
mesh_terms: D000328:Adult; D000485:Allergens; D001985:Bronchial Provocation Tests; D016085:Bronchoconstrictor Agents; D005260:Female; D005541:Forced Expiratory Volume; D006801:Humans; D007073:Immunoglobulin E / Q000097:blood; D008297:Male; D016210:Methacholine Chloride; D008875:Middle Aged; D012130:Respiratory Hypersensitivity / Q000175:diagnosis* / Q000503:physiopathology*
chemical_list: D000485:Allergens; D016085:Bronchoconstrictor Agents; D016210:Methacholine Chloride; D007073:Immunoglobulin E