Christine Y Y Wai1, Nicki Y H Leung2, Agnes S Y Leung2, Yuki Shum2, Patrick S C Leung3, Ka Hou Chu4, Yat Wah Kwan5, Qun Ui Lee5, Joshua S C Wong5, Ivan C S Lam5, Pui Fung Li2, Kary J Y Xu2, Cheuk Yin Lam2, Jinlyu Sun6, Gary W K Wong2, Ting Fan Leung7. 1. Department of Paediatrics, Prince of Wales Hospital, The Chinese University of Hong Kong, Hong Kong; Hong Kong Hub of Paediatric Excellence, The Chinese University of Hong Kong, Hong Kong. 2. Department of Paediatrics, Prince of Wales Hospital, The Chinese University of Hong Kong, Hong Kong. 3. Division of Rheumatology, Allergy and Clinical Immunology, University of California, Davis, Calif. 4. School of Life Sciences, The Chinese University of Hong Kong, Hong Kong. 5. Department of Paediatrics and Adolescent Medicine, Princess Margaret Hospital and Yan Chai Hospital, Hong Kong. 6. Department of Allergy and Clinical Immunology, Peking Union Medical College Hospital, Peking Union Medical College, Beijing, People's Republic of China; Chinese Academy of Medical Sciences, National Clinical Research Center for Dermatology and Immunological Disease, Beijing Key Laboratory of Precision Medicine for Diagnosis and Treatment on Allergic Diseases, Beijing, People's Republic of China. 7. Department of Paediatrics, Prince of Wales Hospital, The Chinese University of Hong Kong, Hong Kong; Hong Kong Hub of Paediatric Excellence, The Chinese University of Hong Kong, Hong Kong. Electronic address: tfleung@cuhk.edu.hk.
Abstract
BACKGROUND: The diagnosis of shellfish allergy currently relies on patient history, skin prick test (SPT), and serum specific IgE (sIgE) quantification. These methods lack sufficient diagnostic accuracy, whereas the gold standard of oral food challenges is risky and burdensome. Markers of reactivity and severity of allergic reactions to shellfish will improve clinical care of these patients. OBJECTIVES: This study compared the diagnostic performance of SPT, sIgE, basophil activation test (BAT), and IgE crosslinking-induced luciferase expression (EXiLE) test for shrimp allergy. METHODS: Thirty-five subjects with documented history of shrimp allergic reactions were recruited and grouped according to results of double-blind, placebo-controlled food challenge (DBPCFC). In addition to routine diagnostics, BAT (Flow CAST) and EXiLE test with shrimp extract and tropomyosin were performed. RESULTS: Of 35 subjects, 15 were shrimp allergic with pruritus, urticaria, and itchy mouth on DBPCFC, whereas 20 were tolerant to shrimp. Tropomyosin only accounted for 53.3% of sensitization among subjects with challenge-proven shrimp allergy. BAT using shrimp extract as stimulant showed the highest area under curve value (0.88), Youden Index (0.81), likelihood ratio (14.73), odds ratio (104), and variable importance (4.27) when compared with other assays and tropomyosin diagnosis. Results of BAT significantly correlated with those of EXiLE (r = 0.664, P < .0001). CONCLUSIONS: BAT is a more accurate diagnostic marker for shrimp allergy than SPT and shrimp sIgE, whereas the EXiLE test based on an IgE crosslinking assay is a good alternative to BAT. Tropomyosin may not be the most important shrimp allergen in Chinese, which warrants further investigation to search for other major allergens and diagnostic markers.
BACKGROUND: The diagnosis of shellfish allergy currently relies on patient history, skin prick test (SPT), and serum specific IgE (sIgE) quantification. These methods lack sufficient diagnostic accuracy, whereas the gold standard of oral food challenges is risky and burdensome. Markers of reactivity and severity of allergic reactions to shellfish will improve clinical care of these patients. OBJECTIVES: This study compared the diagnostic performance of SPT, sIgE, basophil activation test (BAT), and IgE crosslinking-induced luciferase expression (EXiLE) test for shrimp allergy. METHODS: Thirty-five subjects with documented history of shrimp allergic reactions were recruited and grouped according to results of double-blind, placebo-controlled food challenge (DBPCFC). In addition to routine diagnostics, BAT (Flow CAST) and EXiLE test with shrimp extract and tropomyosin were performed. RESULTS: Of 35 subjects, 15 were shrimp allergic with pruritus, urticaria, and itchy mouth on DBPCFC, whereas 20 were tolerant to shrimp. Tropomyosin only accounted for 53.3% of sensitization among subjects with challenge-proven shrimp allergy. BAT using shrimp extract as stimulant showed the highest area under curve value (0.88), Youden Index (0.81), likelihood ratio (14.73), odds ratio (104), and variable importance (4.27) when compared with other assays and tropomyosin diagnosis. Results of BAT significantly correlated with those of EXiLE (r = 0.664, P < .0001). CONCLUSIONS: BAT is a more accurate diagnostic marker for shrimp allergy than SPT and shrimp sIgE, whereas the EXiLE test based on an IgE crosslinking assay is a good alternative to BAT. Tropomyosin may not be the most important shrimp allergen in Chinese, which warrants further investigation to search for other major allergens and diagnostic markers.