Mushroom (Basidiomycete) allergy: diagnosis established by skin test and nasal challenge

Fungal spores are universal components in the air and established as important causes of respiratory allergies. Whereas fungi imperfecti are accepted sources of allergic asthma and rhinitis, the significance of basidiomycetes as respiratory allergens is not established.

The aims of the present study were to investigate the rate of sensitization in subjects referred to an allergy clinic to 3 basidiomycetes commonly found in Europe. We demonstrate the clinical relevance of basidiomycete sensitization by active anterior rhinomanometry and identified basidiomycete allergens by immunoblotting.

Consecutive outpatient clinic attendees (n = 1207, >12 years of age) were given the skin prick test with a panel of common inhalant allergens and extracts of Boletus, Coprinus, and Pleurotus. To evaluate a cause-and-effect relation between basidiomycete allergens and respiratory allergies, 12 Pleurotus pulmonalis spore-sensitized subjects with respiratory symptoms and 6 control subjects were challenged by anterior rhinomanometry. SDS-PAGE immunoblots were used to identify basidiomycete-specific IgE antibodies in sera from subjects with positive skin prick test results. Of 1207 subjects tested, 48 (4%) reacted to at least 1 of the basidiomycete extracts. Whereas all of the 12 subjects with Pleurotus pulmonalis-positive skin test results showed a significant decrease in nasal air flow (mean 73%), none of the control subjects reacted. Immunoblots revealed several different IgE-binding proteins in Pleurotus and Coprinus extracts.

Our results demonstrate that sensitization to basidiomycetes in subjects with respiratory allergies is frequent. Furthermore, Pleurotus pulmonalis spore extracts can definitely induce respiratory allergy in sensitized subjects. Immunoblot assays disclosed different IgE-reactive bands indicating the existence of basidiomycete allergens.