Allergy to shellfish is an increasingly important global health priority, commonly affecting the adult population. Currently, only emergency treatment is available to patients. Molluscs are an important group of shellfish causing allergy but detailed knowledge of their allergens and cross-reactivity between species is limited. This makes it difficult to optimally diagnose patients as well as advise them accurately about allergen avoidance. To date, only tropomyosin has been identified as a pan-allergen in some mollusc species.
AIM: To characterise the allergens of and cross-reactivity between four Australian mollusc species: Sydney Rock Oyster, Blue Mussel, Saucer Scallop and Southern Calamari.
METHODS: Sera from mollusc-allergic patients were used to assess IgE reactivity by ELISA and Western immunoblot to raw and cooked extracts of the four mollusc species. Functional IgE reactivity was evaluated by basophil activation tests. Cross-reactivity between the allergens of the mollusc species as well as to recombinant Por p 1 (Blue Swimmer Crab tropomyosin) was also assessed.
RESULTS: In all assays, cooked oyster, mussel and scallop extracts were more IgE reactive than the raw extracts. However, IgE reactivity decreased with cooking for calamari. IgE immunoblotting identified tropomyosin as a major heat-stable mollusc allergen, with other allergens also playing a role in patient sensitisation. The basophil activation test confirmed biologically relevant IgE reactivity. Oyster and calamari showed the highest degree of cross-reactivity with the other mollusc species. Blue mussel displayed strong IgE cross-reactivity with rPor p1.
CONCLUSIONS: The findings of this study will help pave the way for novel and reliable approaches for diagnosis and management of mollusc allergy.