Triggering of atopic dermatitis by spores of the oyster mushroom Pleurotus pulmonarius

Spores of the basidiomycete Pleurotus pulmonarius a species of the oyster mushrooms are widespread components in the air and established as causes of respiratory allergies. Recent reports indicate that aeroallergens such as mite allergens, pollen or animal dander may play an important role triggering atopic eczema in a subgroup of subjects with atopic dermatitis. The aim of the study was to investigate whether spores of P. pulmonarius may elicit delayed-type skin reactions in atopic subjects particularly in those with an atopic dermatitis. Sixty-five study subjects were categorized prospectively in 4 groups having atopic dermatitis or respiratory allergy with regard to the skin prick test reactivity to P pulmonarius spore extract. Twenty non-atopic individuals served as control subjects. Atopy patch test performed with P. pulmonarius spore extract at a concentration of 1.35 mg protein per gram of petrolatum were evaluated after 48 and 72 hours. Of the subjects with atopic dermatitis, 12 of 37 (32%) showed a positive atopy patch test reaction with 7/13 (54%) also having a positive skin prick test response to the P. pulmonarius spore extract. In the study group with respiratory allergy and positive skin prick test to the Pleurotus extract 1 subject with a well-known asthma had a positive atopy patch test. No positive test reaction was observed in the nonatopic control subjects or in subjects with respiratory allergy but negative skin prick test responses to the P. pulmonarius spore extract. Our results demonstrate that spores of the oyster mushroom P. pulmonarius can induce delayed-type reactions consistent with an acute eczema in atopic individuals, particularly in those with atopic dermatitis. Furthermore, it could be shown that individuals with an air-exposed pattern of the atopic dermatitis were most reactive to the atopy patch tests with these spore extract.