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Boletus edulis: a digestion-resistant allergen may be relevant for food allergy


Correspondence:Dr Arthur Helbling, Division of Allergology, Department of Rheumatology and Clinical Immunology/Allergology, University Hospital, 3010 Bern, Switzerland. E-mail:


Background  Fungal components can cause allergic symptoms either through inhalation, ingestion or contact. Whereas respiratory allergy is thought to be induced by spores, allergic reactions following ingestion are attributed to other parts of the mushroom. Reports of food-related allergic reactions due to the edible mushroom Boletus edulis have occasionally been reported.

Objective  The aim of the study was to investigate whether separate allergens may be detected in alimentary allergy to Boletus edulis.

Methods  Sera of two subjects, one with recurrent anaphylaxis and the other with a predominantly oral allergy syndrome following ingestion of Boletus edulis, have been analysed by a time-course digestion assay using simulated gastric fluid and by SDS-PAGE immunoblotting. Sera of four Boletus edulis skin prick test-negative subjects and all without clinical symptoms to ingested Boletus edulis served as controls.

Results  In lyophilized Boletus edulis extract, at least four water-soluble proteins were detected, the most reactive at 55 kDa and at 80 kDa. Following the time-course digestion assay, IgE binding was found to a 75-kDa protein, but only if the sera of the subject with recurrent anaphylaxis was used.

Conclusion  The data indicate that Boletus edulis can cause an IgE-mediated food allergy due to a digestion-stabile protein at 75 kDa. No IgE immune response to this protein was detected in the serum of a subject with respiratory allergy and oral allergy syndrome to Boletus edulis nor in control sera.