Reactions to Shrimp Including Severe Anaphylaxis in Mite- and Cockroach-Allergic Patients Who Have Never Eaten Shrimp: Clinical Significance of IgE Cross-Reactivity to Tropomyosins From Different Sources

Abstract

Shrimp was obtained from the sea by fisherman, who were instructed to not add any additives and to place the shrimp at -20oC immediately after catching. Shrimp was kept at -20oC, and at the time of use, shrimp was thawed, had their shell removed, and boiled in water for 10 minutes.For the double-blind-placebo-controlled shrimp challenge, shrimp was crushed using a food processor, and added to a mixture of hazelnut cream, oat flakes, milk-based ice cream with small bits of chocolate, powdered chocolate and vanilla extract, containing 15.4 % of fat. Prior to challenge, patients were asked about any reactions to each of the components of the mixture. The cumulative dose of 1g shrimp protein was the maximum we could use to allow shrimp taste to be disguised in the food matrix. Placebo challenges were carried out using the same mixture minus shrimp and similar timing schedule. For the open challenge, cooked shrimp prepared as described for the DBPCFC was lightly salted and seasoned with olive oil. Active and placebo challenges were performed one week apart. IgE ImmunoblotsNatural Lit v 1 and recombinant Per a 7 were prepared in our laboratory according to previously published methods (Santos et al). Protein concentration of shrimp extract, Lit v 1 and Per a 7 was measured by Bradford assay, using Bovine Serum Albumin (BSA) as standard. Fifty micrograms of protein/lane were applied to 10% Sodium Dodecyl Sulfate Polyacrylamide Electrophoresis (SDS-PAGE) gels. Electrophoresis was carried out under reducing conditions with betamercaptoethanol. Protein transferring to nitrocellulose membranes (Millipore, Bedford, MA) was confirmed by Ponceau S staining. Membranes were blocked with Phosphate Buffered Saline (PBS) + 0.1% Tween + 5% skim milk (blocking solution) for 1 hour at room temperature. After

Structural Insights on Cross-Reactivity of Mite Allergens with Helminth Proteins

“…Tropomyosins from HDM have significant homology with tropomyosins from different species and are frequently characterized as involved in the cross-reactivity between mites, shrimp, insects, and helminths [26,28,29,34,47,48,72]. A study in Brazil found patients who were highly IgE-reactive to shrimp tropomyosin but had never eaten shrimp or other crustaceans [73]. This study showed how tropomyosins are conserved and relevant in the cross-reactivity process.…”

Distributional Characteristics Analysis of Allergens in Patients with Allergic Rhinitis in Southern Fujian Province, China

“…This grouping may be related to the phenomenon of antigen crossing. 26 The cockroach-positive rate of AR patients in China is highest in the south, 27 followed by the east (the cockroach-positive rate of AR was lowest in the north). The reported overall positive rate was 19.37%, which is similar to that reported here.…”