Background: A large-scale study of causative allergen components of shrimp allergies has never been conducted in Japan.
Subjects: A total of 31 patients with shrimp allergy who were referred to the Kakogawa Prefectural Medical Center from January 2004 to August 2011 were enrolled in the study. Shrimp allergy was diagnosed according to the clinical symptoms, and positive prick testing using black tiger shrimp.
Methods: Serum-specific IgE to two preparations of shrimp allergens (shrimp: shrimp extracts used before June 2012; and new shrimp: shrimp extracts used after July 2012 for ImmunoCAP®) and tropomyosin was determined with ImmunoCAP® (CAP-FEIA, Phadia) . Western blot analysis was performed using soluble and insoluble fractions from black tiger shrimp to define the causative shrimp allergens.
Results: In 31 cases of shrimp allergy, detection rate (more than class 1) of allergen-specific IgE to conventional shrimp was 58.1%, to new shrimp was 66.7%, and to tropomyosin was 29.0%. Positive rate (more than class 2) of allergen-specific IgE to conventional shrimp was 54.8%, to new shrimp was 55.0%, and to tropomyosin was 19.4%. In the 5 cases of FDEIA, detection rate of allergen-specific IgE to conventional shrimp was 20%, to new shrimp was 40%, and to tropomyosin was 0%. In the 19 cases of immediate-type allergy, detection rate of allergen-specific IgE to conventional shrimp was 68.4%, to new shrimp was 66.7%, and to tropomyosin was 36.8%. In the 7 cases of OAS, detection rate of allergen-specific IgE to shrimp was 57.1%, to new shrimp was 85.7%, and to tropomyosin was 28.5%. Western blot analysis of the 31 cases showed that several cases showed a band with a molecular weight of 35-38 kDa, which corresponds to tropomyosin. However, a 70-kDa band was detected in 30 of 31 cases.
Conclusion: The 70-kDa protein may be a new major allergen component of shrimp allergy.