001414 - Recognition of a Heat-Resistant Beef Allergen: Molecular Analysis in a Patient with Multiple Meat and Fish Allergy

Red meat and fish allergy are uncommon in adolescents and are usually mediated by IgE responses to specific muscle proteins, such as calcium-binding proteins (e.g., parvalbumin) in fish. The coexistence of immediate reactions to both beef and fish raises the question of potential IgE cross-reactivity. We describe the molecular characterization of a heat-resistant beef allergen in a patient with multiple food allergies and investigate possible cross-reactivity with fish allergens.

A 19-year-old atopic patient presented with immediate systemic allergic reactions after ingestion of hake and beef (hamburgers). Skin prick tests showed sensitization to legumes, cereals, and several fish species, as well as positive prick-prick tests with raw and cooked beef and trout. Protein extracts were prepared from raw and cooked beef, trout, sardine, and hake under standardized conditions. Protein and allergenic profiles were analyzed by SDS-PAGE and IgE-Western blot. IgE inhibition assays were performed to assess cross-reactivity between beef and fish extracts.

IgE-Western blot analysis revealed a protein band of approximately 17 kDa recognized by the patient’s serum in both raw and cooked beef extracts, indicating the presence of a heat-resistant beef allergen. In cooked trout extracts, IgE-reactive bands ranging from 100–250 kDa were observed, as well as bands at 17 and 14 kDa. A ~16 kDa IgE-reactive band was detected in raw hake. Inhibition assays demonstrated IgE cross-reactivity between raw and cooked beef at the ~17 kDa band, confirming thermal stability of the allergen. However, no inhibition was observed with trout or hake extracts, ruling out IgE cross-reactivity between beef and fish.

This case describes the recognition of a heat-resistant ~17 kDa allergen in beef, with molecular characteristics consistent with previously reported myoglobin, for which only one similar case has been described in the literature. Despite similarities in molecular weight with certain fish allergens, no cross-reactivity was demonstrated, suggesting independent sensitization. These findings support the existence of clinically relevant, heat-stable allergens in red meat and highlight the importance of molecular diagnostics in complex food allergy phenotypes.