IgE Crosslinking-Induced Luciferase Expression Test as a Sensitive Indicator of Anisakis Allergy

Anisakis allergy has been increasing and the diagnosis of it is based on specific serum IgE detection. Recently, IgE crosslinking-induced luciferase expression (EXiLE) test has been proposed as convenient tool for detecting the functional specific IgE antibodies. Here, we investigated if EXiLE test is a useful tool in the diagnosis of Anisakis allergy. HuRa-40 cells were sensitized using six serum types from three patients with Anisakis allergy at the time of the initial test and after 6–12 months. Thereafter, various concentrations of Anisakis worm protein (AWP) were reacted to measure the degree of EXiLE. The degree of EXiLE was compared with the Anisakis-specific IgE antibody levels measured by the CAP-FEIA method, and the IgE antibody binding protein profile was examined using IgE immunoblotting. Results showed a good correlation between the CAP-FEIA values and EXiLE obtained with 5 μg/mL of AWP (R = 0.91, p < 0.01), a strong response on IgE immunoblot in the region containing proteins weighing ≥40,000 Da. In addition, after the onset of Anisakis allergy, the degree of serum EXiLE decreased in two patients whose Anisakis-specific IgE antibody levels decreased over time but increased in one patient whose specific IgE antibodies increased after repeated antigen sensitization. Based on these data, the AWP-induced EXiLE test seemed to be useful and convenient for the diagnosis of Anisakis allergy, supplementing specific IgE determinants. After allergy onset, the use of this method to observe changes in specific IgE levels over time may be important for predicting the risk of recurrence.