D3.211 - Alpha-Actinin and Hemocyanin as Major Allergens in Crustacean Allergy: A Case Study

Crustacean allergies are a significant cause of severe allergic reactions, often mediated by heat-stable allergens. This study explores the allergenic profile of raw and cooked crustaceans and fish in a patient with reported crustacean allergy triggered by cooking vapors but no history of oral ingestion.

A 35-year-old male with asthma and rhinitis due to dust mites and animal epithelia reported rhinoconjunctivitis and bronchospasm triggered by crustacean cooking vapors since childhood. He tolerates canned tuna and squid but avoids crustaceans entirely. Skin prick tests for raw crustaceans (prawn, shrimp, and lobster) were positive, whereas tests for cooked extracts were negative, indicating a sensitivity to heat-labile allergens.

Protein extracts were prepared from raw and cooked samples of lobster, shrimp, prawn, salmon, sardine, and sole. SDS-PAGE and IgE-Western blot analyses were conducted under reducing conditions to identify allergenic proteins, and proteomics (LC-MS/MS) was used to confirm protein identities.

IgE-Western blot identified strong reactivity to proteins of 75–100 kDa in raw crustacean extracts, corresponding to alpha-actinin (lobster) and hemocyanin (prawn), both confirmed via LC-MS/MS. These proteins were not detected in cooked extracts, explaining the patient's tolerance to heated crustaceans. Fish samples revealed reactivity to 15 kDa proteins (parvalbumins) in salmon and sardine, consistent with known fish allergens.

This study identifies alpha-actinin and hemocyanin as key allergens in crustacean-induced reactions. The disappearance of these proteins upon cooking highlights the importance of allergenic profiling to guide safe dietary recommendations and manage crustacean allergies effectively.