IgE Binding to Raw and Boiled Shrimp Proteins in Atopic and Nonatopic Patients with Adverse Reactions to Shrimp

Abstract

Background: Characterization of seafood allergens is important to understand the immune response to these allergens. Moreover, a detailed comparison between atopic and nonatopic patients with adverse reactions to shrimp has never been reported. Methods: Raw and boiled shrimp extracts were analyzed by immunoblotting using sera from 9 atopic and 7 nonatopic patients with a history of adverse reactions to shrimp, and 13 control subjects. Total IgE, specific IgE and skin prick tests (SPT) to shrimp were also investigated. Results: The level of specific IgE to shrimp was higher in atopic patients than nonatopic patients (p < 0.05). Symptoms, SPT results and major allergens involved were similar in atopic and nonatopic patients. The 16.5-kD protein had the highest frequency of IgE binding followed by the 40-kD protein in these patients. Other minor IgE-binding proteins were observed at the 20-, 22-, 54-, 72-, 129- and 140-kD regions. Patients who had binding to the 16.5-kD protein had either positive (25% raw/31% cooked) or negative (13% raw/cooked) CAP-FEIA-RAST, while patients who recognized the 40-kD protein all had positive (31% raw/19% cooked) CAP-FEIA-RAST. All control subjects had negative immunoblots for these two proteins. Conclusion: The 16.5-kD protein was the most frequent protein identified regardless of CAP-FEIA-RAST results, while the 40-kD protein was only present in patients with positive CAP-FEIA-RAST. Therefore, 16.5-kD protein may be an important allergen that is clinically relevant in both atopic and nonatopic patients with adverse reactions to shrimp even if it is not detected by the CAP-FEIA-RAST system.