Purpose: Sensitization to A fumigatus allergens triggers IgE mediated allergic reactions and increases the severity of asthma and related allergic diseases. Current diagnostic modalities employ crude Aspergillus extracts which only indicate the source to which the patient has been sensitized, without identifying the number and type of allergens in crude extracts. However, clinical sensitivity of a patient depends on the number and type of allergens against which they have developed IgE antibodies. We report a study on the identification of major and minor allergens of the crude Aspergillus fumigatus extract and heterogeneity of patients’ IgE response to them. Methods: Skin prick tests were performed on 300 patients of bronchial asthma and/or allergic rhinitis and 20 healthy volunteers. Allergen specific IgE in patients’ sera was estimated by enzyme allergosorbent test (EAST). Immunoblots were performed to identify major/minor allergens of A fumigatus extract and study heterogeneity of patients’ IgE response to them. Results: Positive cutaneous responses were observed in 19.7%of patients with A fumigatus extract. Corresponding EAST positivity was 66.7%. Twelve allergenic proteins were detected in crude extract ranging from 20.2-96.7 kda (20.2, 30.5, 32.3, 34, 37, 40, 56.2, 60.7, 77.6, 82.7, 90 and 96.7 kDa). Of these, four were major allergens (90, 82.7, 34 and 20.2 kDa). The position and slopes of EAST binding and inhibition curves obtained with individual sera varied from patient to patient. Different patients’ sera showed variable IgE-binding to Aspergillus allergens in individual immunoblots. The number and molecular weight of IgE-binding proteins in A fumigatus extract varied among patients. Conclusion: These results gave evidence of heterogeneity of patients’ IgE response to major/minor Aspergillus allergens. These findings emphasize the importance of component resolved diagnosis i.e. identification of allergen binding IgE profile of an individual. This patient-tailored diagnosis will be helpful in identifying actual disease eliciting molecules in an individual and may improve allergen-specific immunotherapy.
Full conference title:
The 8th Advances Against Aspergillus, Lisbon Conference Center, Lisbon, Portugal
- AAA 8th (2018)