Orthologous Allergens and Diagnostic Utility of Major Allergen Alt a 1
Related Experiment Video
Updated: Mar 19, 2026
Basophil Activation Test for Allergy Diagnosis
Published on: May 31, 2021
Antonio Moreno1, Fernando Pineda2, Javier Alcover3
1Allergy Service, Hospital of Cuenca, Cuenca, Spain.
Purpose:
Hypersensitivity to fungi is associated with rhinoconjunctivitis and asthma. For some fungi, such as Alternaria alternata (A. alternata), the symptoms of asthma are persistent, increasing disease severity and the risk of fatal outcomes. There are a large number of species of fungi but knowledge of them remains limited. This, together with the difficulties in obtaining adequate standardized extracts, means that there remain significant challenges in the diagnosis and immunotherapy of allergy associated with fungi. The type of indoor fungi related to asthma/allergy varies according to geographic, climatic, and seasonal factors, making their study difficult. The aim of this study was to determine hypersensitivity to indoor fungi in a population from Cuenca, Spain.
Methods:
Thirty-five patients with symptoms compatible with rhinitis or asthma who showed clear worsening of their symptoms in their homes or workplace were included. In vivo and in vitro tests were made with a battery of fungal allergens, including the species isolated in the home or workplace.
Results:
Ulocladium botrytis (U. botrytis) and A. alternata were the most representative species as a source of home sensitization. These species showed very high concordance in skin tests, specific IgE, and histamine release. The allergen Alt a 1, which was recognized in all patients, was detected in A. alternata, U. botrytis, and Stemphylium botryosum (S. botryosum).
Conclusions:
U. botrytis and A. alternata were the most representative species as a source of home sensitization. Alt a 1 was recognized in all patients and may be considered a non-species-specific allergen that could be used as a diagnostic source of sensitization to some species of the Pleosporaceae family.
Insights
Indoor fungi like Alternaria alternata and Ulocladium botrytis are common causes of allergies and asthma. The allergen Alt a 1, found in these fungi, may be a key diagnostic marker for sensitization.
Area of Science:
- Allergen immunotherapy
- Environmental microbiology
- Clinical immunology
Background:
- Fungal hypersensitivity is linked to allergic respiratory diseases like asthma and rhinoconjunctivitis.
- Persistent asthma symptoms due to fungi, such as Alternaria alternata, increase disease severity and mortality risk.
- Limited knowledge of fungal species and challenges in obtaining standardized extracts hinder accurate diagnosis and effective immunotherapy for fungal allergies.
Purpose of the Study:
- To investigate hypersensitivity to indoor fungi in a Spanish population.
- To identify prevalent indoor fungi causing allergic reactions in Cuenca, Spain.
Main Methods:
- Inclusion of 35 patients with rhinitis or asthma symptoms exacerbated by their home or work environment.
- Performance of in vivo and in vitro tests using a panel of fungal allergens, including those isolated from patients' environments.
Main Results:
- Ulocladium botrytis and Alternaria alternata were identified as the most significant sources of indoor fungal sensitization.
- High concordance was observed across skin tests, specific IgE, and histamine release assays for these species.
- The allergen Alt a 1 was detected in Alternaria alternata, Ulocladium botrytis, and Stemphylium botryosum, and recognized by all patients.
Conclusions:
- Ulocladium botrytis and Alternaria alternata are key indoor fungi responsible for sensitization.
- Alt a 1, recognized by all patients, shows potential as a non-species-specific allergen for diagnosing sensitization within the Pleosporaceae family.
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