The use of raw or boiled crustacean extracts for the diagnosis of seafood allergic individuals

Background Seafood plays an important role in human nutrition and is responsible for severe hypersensitivity reactions. Objective To evaluate how the cooking process may alter the in vivo and in vitro allergenicity of these extracts. Methods Raw and boiled extracts of shrimps and 2 types of lobsters were manufactured. Boiled extracts were prepared after the raw material was boiled for 15 minutes in phosphate-buffered saline. Raw and boiled extracts were homogenized and extracted for 4 hours. Afterward, the extracts were centrifuged, dialyzed, filtered, and freeze-dried. Seventy-eight patients were skin prick tested with these raw and boiled extracts. Specific IgE against the 6 extracts was measured by enzyme-linked immunosorbent assay (ELISA). Immunoblots and ELISA inhibition studies were performed with a pool of sera. Results In vivo results showed that boiled extracts induced statistically significant larger wheals than raw extracts. More patients with positive results were also detected with boiled extracts. In vitro experiments by direct ELISA confirmed the in vivo results. The protein content in the boiled extracts decreased, and important differences were detected by sodium dodecyl sulfate-polyacrylamide gel electrophoresis. Crossreactivity experiments showed that both types of extracts retained similar allergenic characteristics, even if the immunoblots revealed some differences in IgE binding. Conclusions More patients were identified using boiled extracts of shrimp and American and spiny lobsters than with raw extracts. The wheal sizes of the skin test reactions and specific IgE levels were also significantly greater using boiled extracts. The use of boiled extracts seems to be more effective in diagnosing seafood allergy.