Anaphylaxis caused by the ingestion of cultivated mushroom (Agaricus bisporus): Identification of allergen as mannitol.

The role of mushroom spores as
inhalants in causing respiratory allergy has been well
established. Although mushrooms are commonly used
as food throughout the world, food allergy to mushrooms
is not very common. A severe case of anaphylaxis
in a 32-year-old woman who experienced facial
edema and generalized urticaria minutes after eating
mushroom curry is presented herein. The purpose of
the present study was to identify the putative allergen
in the cultivated mushroom Agaricus bisporus.
Methods: A combination of biochemical fractionation/
analytical techniques (gel filtration, ultrafiltration,
ion-moderated cation-exchange chromatography,
high-pressure liquid chromatography and gas
chromatography–mass spectrometry (GC-MS)) and
allergy diagnostic tests (skin prick test (SPT), allergenspecific
IgE) were used.
Results: The SPT with mushroom extract was strongly
positive; however, allergen-specific IgE could not be
detected by enzyme-linked immunosorbent assay. The
SPT was also positive with cooked, steamed or dried
mushroom extracts, suggesting the presence of a heatstable
allergen. Gel filtration of mushroom extract
on Sephadex G-25, as analyzed by SPT, indicated
the presence of a low molecular weight (< 1 kDa)
allergen. Using ion-moderated cation-exchange chromatography,
the allergen was isolated and identified as
mannitol based on skin reactivity. Mannitol was confirmed
by GC-MS analysis.
Conclusions: This is the first report of food allergy to
cultivated mushroom A. bisporus and also the first
report describing a low molecular weight allergen
(mannitol) in mushroom.