Allergic reactions to genus Morus plants: a review

Mulberry is a plant belonging to the family Moraceae, and genus Morus. Allergic sensitization to mulberries has been reported as both food allergy or respiratory allergy, and cross-reactivity between mulberries and other pollens or fruits was described. Clinically, in the articles reporting mulberry allergy, the reactions included respiratory allergy, airborne contact urticaria, anaphylaxis, oral allergy syndrome, and food induced urticaria. As far as cross-reactivity is concerned, the allergens identified thus far in mulberries include pathogenesis-related (PR)10 proteins, with sequence identity to Bet v 1 from birch, lipid transfer (LTP)1 proteins with identity with LTPs from Rosaceae family plants, panallergens groups, and also ubiquitin-like protein and cystatin-like protein. The two latter proteins account for cross-reactions with Parietaria judaica and Olea europaea. Such large cross-reactivity warrants to pay particular attention to the risk of systemic reactions to foods, particularly in subjects sensitized to birch, parietaria or olive pollens. In fact, the increasing use of mulberry as a food product, which is encouraged by its remarkable antioxidant power, expose sensitized patients to possible reactions after ingesting foods, dietary supplements or nutraceuticals containing mulberry. Mulberry allergenicity can vary according to the processing methods used since some allergens are thermostable and other loss their reactivity during heating.