Identification and characterization of allergens in two species of tuna fish

In countries where fish consumption is high, allergenic reactions to fish are common among patients diagnosed with food hypersensitivity. For tuna fish, allergenic proteins are not known. In addition, it is not known how the tuna fish extracts should be processed to obtain optimal in vitro diagnostic performance and to preserve labile antigens.

The aim of this study was to characterize IgE-binding components of Yellowfin and Albacore tuna fish.

Various tuna fish extract preparations were fractionated by sodium dodecylsulfate-polyacrylamide gel electrophoresis and transferred to nitrocellulose and analyzed by using tuna positive patients with different Western blot profiles. The functional activity of the extracts was evaluated by basophil histamine release.

Immunoblot analysis showed the majority of patients responding to Yellowfin tuna extract. Inhibition studies using immunoblot analysis and histamine release testing showed a specific protein with a molecular weight of approximately 46 kD that is present in Yellowfin tuna, but absent in Albacore. Only defatted, lyophilized tuna fish extracts were able to induce histamine release from sensitized basophils although IgE-binding components were detected in fresh raw, fresh cooked, and canned tuna fish preparations.

These studies indicate that patient sera may contain different tuna fish species IgE specific antibodies directed against unique species specific allergens present in Yellowfin and Albacore tuna fish. Possibly, extracts should contain specific allergenic components from both Albacore and Yellowfin to cover the epitope heterogeneity observed in sera from patients developing IgE antibodies against tuna fish.