title: Allergen-specific IgE as a biomarker of exposure plus sensitization in inner-city adolescents with asthma.
abstract: BACKGROUND
  Relationships among allergen-specific IgE levels, allergen exposure and asthma severity are poorly understood since sensitization has previously been evaluated as a dichotomous, rather than continuous characteristic.
  
  
  METHODS
  Five hundred and forty-six inner-city adolescents enrolled in the Asthma Control Evaluation study underwent exhaled nitric oxide (FE(NO)) measurement, lung function testing, and completion of a questionnaire. Allergen-specific IgE levels and blood eosinophils were quantified. Dust samples were collected from the participants' bedrooms for quantification of allergen concentrations. Participants were followed for 12 months and clinical outcomes were tracked.
  
  
  RESULTS
  Among sensitized participants, allergen-specific IgE levels were correlated with the corresponding settled dust allergen levels for cockroach, dust mite, and mouse (r = 0.38, 0.34, 0.19, respectively; P < 0.0001 for cockroach and dust mite and P = 0.03 for mouse), but not cat (r = -0.02, P = 0.71). Higher cockroach-, mite-, mouse-, and cat-specific IgE levels were associated with higher FE(NO) concentrations, poorer lung function, and higher blood eosinophils. Higher cat, dust mite, and mouse allergen-specific IgE levels were also associated with an increasing risk of exacerbations or hospitalization.
  
  
  CONCLUSIONS
  Allergen-specific IgE levels were correlated with allergen exposure among sensitized participants, except for cat. Allergen-specific IgE levels were also associated with more severe asthma across a range of clinical and biologic markers. Adjusting for exposure did not provide additional predictive value, suggesting that higher allergen-specific IgE levels may be indicative of both higher exposure and a greater degree of sensitization, which in turn may result in greater asthma severity.
authors.affiliation: Johns Hopkins University School of Medicine, Baltimore, MD, USA. ematsui1@jhmi.edu
authors.forename: E C
authors.initials: EC
authors.lastname: Matsui
authors.forename: H A
authors.initials: HA
authors.lastname: Sampson
authors.forename: H T
authors.initials: HT
authors.lastname: Bahnson
authors.forename: R S
authors.initials: RS
authors.lastname: Gruchalla
authors.forename: J A
authors.initials: JA
authors.lastname: Pongracic
authors.forename: S J
authors.initials: SJ
authors.lastname: Teach
authors.forename: P J
authors.initials: PJ
authors.lastname: Gergen
authors.forename: G R
authors.initials: GR
authors.lastname: Bloomberg
authors.forename: J F
authors.initials: JF
authors.lastname: Chmiel
authors.forename: A H
authors.initials: AH
authors.lastname: Liu
authors.forename: M
authors.initials: M
authors.lastname: Kattan
authors.forename: C A
authors.initials: CA
authors.lastname: Sorkness
authors.forename: S F
authors.initials: SF
authors.lastname: Steinbach
authors.forename: R E
authors.initials: RE
authors.lastname: Story
authors.forename: C M
authors.initials: CM
authors.lastname: Visness
mesh_terms: D000293:Adolescent; D000485:Allergens / Q000276:immunology; D000818:Animals; D001249:Asthma / Q000097:blood* / Q000276:immunology; D015415:Biomarkers / Q000097:blood*; D002648:Child; D045853:Exhalation; D005260:Female; D006801:Humans; D006967:Hypersensitivity / Q000097:blood / Q000276:immunology; D007073:Immunoglobulin E / Q000097:blood*; D008297:Male; D009569:Nitric Oxide / Q000032:analysis; D012129:Respiratory Function Tests; D014505:Urban Population; D055815:Young Adult
chemical_list: D000485:Allergens; D015415:Biomarkers; D009569:Nitric Oxide; D007073:Immunoglobulin E