Allergy To Shrimp: A Double Blind, Placebo-controlled, Food Challenge Study And Allergens Implicated In Spain.

Abstract

RATIONALE: Our study aimed to investigate clinical characteristics and allergens recognized by patients with suspected shrimp allergy. METHODS: We studied 35 patients with suspected allergic reactions to shrimp, mostly urticaria. In all patients double-blind placebo controlled oral challenge (DBPCOC) was performed. Prick-by-prick tests and serum specific IgE (CAP system) with mites, anisakis, mosquito, cockroach, shrimp, clam, snail, mussel, scallop, cockle, squid, octopus and cuttlefish were performed as well as IgE to rPen a1 (tropomyosin). All patient's sera were tested individually by IgE immunodetection after SDS-PAGE with shrimp crude extract. Seven patients sensitized to mites and with good tolerance to shrimp were included as controls. RESULTS: 20 (57%) patients were considered allergic (14 + DBPCOC and 6 anaphylaxis). Specific IgE was positive to all of extracts tested by CAP, except in 2 patients. 17 were sensitized to mites. All but 2 had specific IgE to tropomyosin, in 1 only detected by immunoblotting. In patients with negative DBPCOC, 5 had specific IgE to other seafood and 10 to mites. In the control group all CAP determinations were negative except in one patient who had specific IgE to shrimp and other patient a 37 kDa IgE-binding band. Immunoblots demonstrated several IgE binding-bands. The main bands were of 37 and 20 kDa in 12 allergic patients. These bands were also detected in 3 patients with negative DBPCOC. CONCLUSIONS: This study shows the need to perform food challenges for a correct diagnosis. Tropomyosin seems the major allergen in shrimp allergic patients in Spain, although, other allergens may be implicated.