A pediatric case of anaphylaxis caused by matsutake mushroom (Tricholoma matsutake) ingestion.

BACKGROUND Anaphylaxis is one of the severest forms of allergic diseases. Some kinds of mushroom are known as causative allergens in food anaphylaxis. Matsutake mushroom (Tricholoma matsutake) is a typical edible mushroom available in autumn in Japan. We encountered an 8-year-old Japanese girl who developed anaphylaxis after ingesting matsutake mushrooms. METHODS We studied the case in detail, by measuring specific IgE antibodies and conducting skin tests, to confirm the diagnosis. We also detected seven cytokines and chemical mediators in the blood in order to study the pathophysiology of the anaphylaxis. RESULTS We diagnosed anaphylaxis caused by ingestion of matsutake mushrooms based on the following. A skin prick test showed a positive reaction to matsutake mushroom, and specific IgE antibody for matsutake mushroom extract was detected in the patient's serum by fluorometric ELISA. Blood levels of chemical mediators including histamine, ECP, tryptase and cytokines such as IL-6, IL-5 and IL-10 but not IFN-gamma also increased significantly during the allergic episode. CONCLUSIONS We demonstrated that chemical mediators including histamine, tryptase and ECP as well as several cytokines were involved significantly during the episode of anaphylaxis. In addition, eosinophils as well as mast cells played significant roles in the anaphylaxis. Furthermore, CD4+CD25+ T regulatory cells that released IL-10 were likely activated during the anaphylaxis. Matsutake mushroom should be considered as a causative allergen in food anaphylaxis.