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, while the gold standard of oral food challenges are risky and burdensome. Markers of reactivity and severity of allergic reactions to shellfish will improve clinical care of these patients.
This study compared the diagnostic performance of SPT, sIgE, basophil activation test (BAT) and IgE crosslinking-induced luciferase expression (EXiLE) test for shrimp allergy.
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.
15/35 subjects were shrimp-allergic with pruritus, urticaria and itchy mouth on DBPCFC while 20/35 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 AUC 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).
BAT is a more accurate diagnostic marker for shrimp allergy than SPT and shrimp sIgE, while EXiLE test based on 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.

Copyright © 2020. Published by Elsevier Inc.