Positive Bronchial Challenges to D. Pteronyssinus in Asthmatic Subjects in Absence of Systemic Atopy

Abstract

RATIONALE: Studies show evidence of positive responses to nasal challenge to allergens in subjects with rhinitis without systemic atopy (negative skin testing and serum specific IgE) and demonstrate inflammatory changes and local production of IgE. We present 2 cases of positive bronchial challenges to d. Pteronyssinus in subjects with asthma and no systemic atopy METHODS: Two subjects with mild-moderate perennial non-allergic asthma (ANA) and rhinitis, suggestive symptoms of allergy to dust mites, negative skin testing and specific IgE to d. Pteronyssinus were evaluated. Six subjects with allergic asthma (AA) due to d. Pteronyssinus and 2 healthy subjects were included as controls. Bronchial challenge was performed with d. Pteronyssinus extract at 4 μg/ml of Der. p1. Serial metacholine challenge and induced sputum were performed prior to and 24 hours after challenge. Cell populations were evaluated by flow cytometry RESULTS: All ANA and AA cases had immediate positive response to d. pteronyssinus with ≥20% fall in FEV1. All ANA/AA subjects had positive methacholine challenge, and PC20 decreased in both groups 24 hours after allergen challenge (n.s), negative in controls (PC20 > 16 mg/ml). Sputum ECP was higher in AA after challenge compared to ANA and controls. However, in both ANA cases % of sputum eosinophils increased after challenge. Sputum and serum basophils were higher in AA and ANA compared with controls. CONCLUSIONS: We report two cases of positive bronchial responses to d. pteronyssinus in subjects with suggestive symptoms but with no evidence of systemic atopy. Further studies are required to increase the number of cases.