The existence of a dose-response relationship between indoor
allergen exposure and sensitization has been widely described, but the effect of
allergen exposure on
asthma activity (symptoms, bronchial hyperresponsiveness [BHR], and
inflammation) is not clear. Our aim was to determine the existence of an association among current exposure to mite
allergens and symptoms, BHR, and airway
inflammation assessed in blood and sputum from asthmatic patients sensitized to Dermatophagoides pteronyssinus. We selected 31 mild and recently diagnosed (12-24 months)
asthma patients sensitized to D. pteronyssinus. Allergenic exposure (
Der p 1, Der 2) was assessed by a commercial assay based on
monoclonal antibodies (mAb), carried out on the dust samples collected from patients' beds in a standardized way. Patients completed an
asthma symptom questionnaire and underwent skin tests,
methacholine bronchial challenge, and sputum induction. Sputum cell profile was analyzed and
eosinophil cationic protein (ECP),
tryptase,
albumin, and interleukin(IL)-5 levels were quantified in sputum supernatant. Total eosinophil numbers and ECP levels were measured in blood samples. Most patients were exposed to
Der p 1 levels under 2 microg/g of dust.
Der p 1 exposure was higher among the subjects with positive sputum
tryptase detection (P = 0.020).
Der p 1 levels showed a trend toward correlation with
asthma symptoms (P = 0.066, r = 0.36) and correlated with sputum
tryptase levels (P = 0.032, r = 0.42). No relationship between BHR, eosinophilic
inflammation, and allergenic exposure was found. Our results suggest that
asthma symptoms and lung mast-cell activation are at least partially dependent on current
allergen exposure. The lack of correlation between mite exposure, eosinophilic
inflammation, and BHR supports the role of other factors that enhance the immunologic response initiated by
allergen, increasing the activity of
asthma.