IgE binding to raw and boiled shrimp proteins in atopic and nonatopic patients with adverse reactions to shrimp.

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.