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Updated: Jun 22, 2026
Investigating Mast Cell Secretory Granules; from Biosynthesis to Exocytosis
Published on: January 26, 2015
Aspergillus fumigatus induces immunoglobulin E-independent mast cell degranulation
Mirjam Urb1, Philippe Pouliot, Fabrice N Gravelat
1Department of Microbiology, McGill University, Montréal, Québec, Canada.
Background:
Pulmonary colonization by Aspergillus fumigatus in chronic lung disease is associated with progressive decline in lung function even in the absence of specific allergic response. We hypothesized that A. fumigatus contributes to this decline by inducing pulmonary mast cell degranulation even in the absence of antigen-specific immunoglobulin E (IgE). Therefore, we investigated whether A. fumigatus can induce mast cell degranulation independently of IgE.
Methods:
We studied the interactions of Aspergillus species with mast cells in the absence of IgE in vitro with use of scanning electron microscopy. The extent of mast cell degranulation was quantified by measuring the release of beta-hexosaminidase.
Results:
Mature A. fumigatus hyphae induced mast cell degranulation in the absence of IgE. Hyphae of Aspergillus flavus, Aspergillus niger, and Aspergillus nidulans induced much less mast cell degranulation. Mast cell degranulation required direct contact with mature A. fumigatus hyphae, and was not induced by conidia or immature hyphae. Killed hyphae induced significant degranulation, whereas live hyphae from mutants deficient in the fungal development regulators StuA and MedA induced very little degranulation.
Conclusions:
Factors expressed on the surface of mature A. fumigatus hyphae that are controlled by StuA and MedA induce mast cell degranulation in the absence of IgE.
Insights
Aspergillus fumigatus hyphae trigger mast cell degranulation without IgE, contributing to lung function decline in chronic lung disease. This process involves direct contact with mature hyphae, independent of allergic responses.
Area of Science:
- Immunology
- Mycology
- Pulmonology
Background:
- Pulmonary colonization by Aspergillus fumigatus is linked to lung function decline in chronic lung diseases.
- This decline occurs even without a specific allergic response, suggesting non-allergic mechanisms.
- Investigating Aspergillus fumigatus's role in mast cell activation independent of IgE is crucial.
Purpose of the Study:
- To determine if Aspergillus fumigatus can induce mast cell degranulation independently of immunoglobulin E (IgE).
- To explore the mechanisms by which A. fumigatus interacts with mast cells in the absence of allergic sensitization.
Main Methods:
- In vitro study of Aspergillus species interacting with mast cells without IgE.
- Utilized scanning electron microscopy to visualize interactions.
- Quantified mast cell degranulation by measuring beta-hexosaminidase release.
Main Results:
- Mature Aspergillus fumigatus hyphae induced mast cell degranulation independently of IgE.
- Direct contact with mature hyphae was essential; conidia and immature hyphae did not induce degranulation.
- Hyphae regulated by StuA and MedA showed reduced degranulation, indicating the role of specific fungal factors.
Conclusions:
- Surface factors on mature A. fumigatus hyphae, controlled by StuA and MedA, trigger mast cell degranulation without IgE.
- This IgE-independent mast cell activation by A. fumigatus may contribute to lung function deterioration in chronic lung diseases.
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