Identification of raw and cooked snow crab proteins that elicit IgE reactivity in snow crab processing workers

Abstract Rationale Snow crab proteins produce IgE-mediated reactions in crab processing workers. We sought to identify and compare the relevant allergenic proteins in raw crab (RC) and cooked crab (CC). Methods Sera were selected based on IgE reactivity to RC (8), CC (3), or both (3). RC and CC meat proteins were separated by SDS-PAGE electrophoresis, transferred to nitrocellulose membranes incubated with the IgE-reactive sera and then 125 I-anti-IgE. IgE-reactive proteins were detected by autoradiography. Competitive immunoassay using RC or CC inhibitors ranging from 500μg to 0.001μg concentrations was performed to compare RC and CC allergens. Results RC and CC-reactive sera detected three proteins in RC and CC (14.4 kD, 18.5 kD, and 25.1 kD proteins). There were 5 additional reactive proteins identified only in RC (including 28.2 kD, 34 kD, and 40.7 kD proteins), and several proteins (14.4 kD to 54.3 kD) identified only in CC. IgE inhibition revealed that 10 μg of RC inhibited RC sera pool 76%; whereas 10 μg of CC did not inhibit RC sera pool significantly (8%). Similarly, 1μg of CC inhibited CC sera pool 86%, whereas 1μg of RC only inhibited CC sera pool 44%. Conclusions Three IgE-reactive proteins were common to RC and CC. Five other IgE-reactive proteins identified in RC were not present in CC. IgE inhibition results demonstrate a difference in the allergenic content of RC and CC. Additional studies will further identify allergens in RC and CC and determine their role in occupational allergy of crab workers.