Abstract
The increase in the number of food allergy cases is a serious social problem in developed countries. In Japan, where seafood provides 40 % of animal protein intake, seafood is recognized as one of the major allergenic foods, the other three being egg, milk, and wheat. The morbidity of seafood-allergic patients has reached 10 % among elementary school children and their families, and seven kinds of seafood (shrimp, crab, abalone, squid, salmon, mackerel, and salmon roe) are listed as allergenic foods in Japan's food allergen labeling system.
Seafood contains IgE-reactive proteins, which act as a trigger for immediate hypersensitivity. Parvalbumin and collagen in fish meat, tropomyosin in invertebrates (shellfish/mollusk, prawn, crab, squid and octopus), and β'-component in fish roe were identified as seafood allergens and their structures were clarified. The widely ranged IgE cross-reactivity is a common characteristic of seafood allergens. For example, people suffering from a fish allergy have specific IgE that reacts with more than one fish parvalbumin, and salmon-roe-llergic patients' sera contain specific IgE that react with β'-component of another fish. Additionally, invertebrate tropomyosin, called “pan-allergen,” contains IgE- binding sites with similar amino-acid sequences to each other. Apparently, the information of allergen cross-reactivity contributes to ensuring food safety and preventing excess evasion of seafood materials in dietary instruction for allergic patients; for example, fish roe has no cross-reaction with egg. This review introduces the characteristic of seafood allergens and their allergen-cross reactivity.
