Shrimp allergy: Analysis of commercially available extracts for in-vivo diagnosis short title: Analysis of commercial shrimp extracts for SPT

Background: SPT with commercial extracts represent the first step of the diagnosis of shrimp allergy but their clinical efficiency is undefined. Objective: To analyze the clinical usefulness of all commercial extracts of crustaceans for SPT available in Italy. Methods: One hundred fifty-seven shrimp-allergic patients underwent SPT with five commercial extracts of crustaceans and with house dust mite (HDM) extract in a multicenter study. Commercial extracts were analyzed by SDS-PAGE and compared with a freshly prepared in house shrimp extract. IgE to Pen a 1/Pen m 1; Pen m 2, and Pen m 4 were detected and immunoblot analysis was carried on a large number of sera. Results: Commercial crustaceans extracts gave extremely inhomogeneous skin reactions resulting in 32 different clinical profiles, showed marked differences in protein content, and sometimes lacked proteins at molecular weights corresponding to those of major shrimp allergens. Only strong Pen a 1/Pen m 1 reactors reacted to both HDM and all 5 commercial extracts on SPT. Most patients, including tropomyosin-negative ones, reacted to HDM. Patients reacted to a variable and large array of proteins and IgE reactivity at high molecular weights (> 50 kDa) was frequently detected. Conclusions: The in-vivo diagnosis of shrimp allergy must be still based on SPT with fresh material. Shrimpallergic patients frequently react to a numberof ill-defined high molecular weight allergens which makes currently available molecules for the component-resolved diagnosis largely insufficient. Mites and crustaceans probably share several allergens other than tropomyosin.