Detection of a novel 20 kDa shrimp allergen showing cross-reactivity to house dust mites

D. Villalta, E.Tonutti, D. Visentini, N. Bizzaro, D. Roncarolo, S. Amato, G. Mistrello

Background: Allergy to crustacean shellfish is one of the most common IgE-mediated food allergies, and tropomyosin has been identified as the major allergen. However, not all subjects affected by this allergy are IgE-positive to tropomyosin. Aims: To evaluate whether sera of patients with shrimp allergy but negative for tropomyosin react to other allergen(s); and to evaluate the role such allergen(s) may play in cross-reactivity between crustaceans and house dust mites (HDMs). Methods: Three different pools of sera-one from subjects with shellfish allergy and HDMs positivity, but negative for recombinant and native tropomyosin (rPen a 1 and nPen m 1) (Pool 2); a second from subjects with tropomyosin and HDMs positivity (Pool 1); and the last from subjects allergic only to HDMs (Pool 3) were submitted to immunoblotting. Subsequently, a 20 kDa protein-enriched fraction of shrimp extract was used at two different concentrations (10 and 100 ìg/mL) to pre-absorb the Pool 2 serum and to evaluate, by ELISA assay, the level of inhibition on shrimp and HDMs-coated wells, respectively. Results: The Pool 2 serum showed IgE reactivity against a 20 kDa component. Its pre-absorption with an enriched fraction of 20 kDa protein caused an inhibition of 56% in IgE binding to shrimp extract at a concentration of 100 ìg/mL, and of 14% and 35% to HDMs extract at concentrations of 10 and 100 ìg/mL, respectively, as measured by ELISA assay. Conclusions: The 20 kDa component seems to be a new crustacean allergen and it could play a role in cross-reactivity with HDMs.
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