The present situation and prospect about pollen-food allergy syndrome

Pollen-food allergy syndrome (PFAS), also called “oral allergy syndrome”, is a class 2 food allergy that is induced by cross-reaction between pollen allergens and food allergens. It is mainly limited to the oral mucosa, but in some cases, PFAS induces allergic reactions in the nose, eyes, skin, and respiratory system, while also causing shock. PFAS is caused by allergens having high homology to various foods and pollen pan-allergens, and once it develops, it begins to induce allergic reactions to various foods and pollens. In Japan, PFAS is predominantly caused by pollens of the Betulaceae family, including PR-10/Bet v1 related proteins, and pollens of the Gramineae family, including profilins. However, single-sensitization to Japanese cedar pollen is not a risk factor for PFAS. Moreover, it is difficult to prove the existence of specific IgE causing food allergy in PFAS. Instead, it is recommended to measure pollen-specific IgE, which has cross-reactivity to food allergens. Although PFAS is generally prevented by avoiding eating foods that induce allergic reactions, in the case of PFAS caused by PR-10/Bet v1 related proteins and profilins, it is possible to eat cooked foods because heat deactivates antigenicity. However, precautions should be taken when PFAS is caused by foods containing Gly m 4 (soybean) and LTP because these allergens have heat-resistant properties. The measurement of Gly m 4 is already useful and applicable to insurance.