鈴木 加余子

INTRODUCTION: Screening for ω-5 gliadin specific IgE antibody (sIgE) has high diagnostic utility in cases of suspected wheat-dependent exercise-induced anaphylaxis (WDEIA); however, negative cases may require confirmatory tests, such as the oral challenge test. Thus, newly identified allergens that can be used for the serological diagnosis of WDEIA are needed. This study aimed to identify additional sIgE biomarkers of WDEIA. METHODS: Forty-two patients with WDEIA (5 negative/37 positive for ω-5 gliadin sIgE) were enrolled. For comparison, 8 patients with immediate-type wheat allergy without WDEIA and 20 healthy controls without wheat allergy were also enrolled. Extracted wheat proteins were separated by 2D-PAGE. Proteins that reacted with serum IgE antibody in 2D Western blotting (2D-WB) were identified using mass spectrometry. Recombinant proteins were synthesized in Escherichia coli, and the antigenicity was tested using ELISA and the basophil activation test. RESULTS: In 2D-WB, nine proteins reacted with the serum IgE antibody from at least 60% of patients with WDEIA (n ≥ 25/42). ELISA revealed that alpha/beta gliadin MM1 exhibited the highest positive immunoreactivity in 23 of 26 patients who were positive for ω-5 gliadin sIgE (88%) and in 5 of 5 patients who were negative for ω-5 gliadin sIgE (100%). Alpha/beta gliadin MM1 exhibited significantly higher basophil activation in 14 patients with WDEIA when compared to 5 individuals without a wheat allergy. CONCLUSIONS: Alpha/beta gliadin MM1 sIgE exhibited the highest seropositivity, even among patients who were negative for ω-5 gliadin sIgE. The inclusion of alpha/beta gliadin MM1 in allergen-sIgE tests may improve the sensitivity for diagnosing WDEIA.

BACKGROUND: Immediate allergy caused by natto, a popular Japanese food prepared by fermenting soybeans with Bacillus subtilis var. natto, has been reported. Polygamma glutamic acid (PGA) in the sticky substance around natto beans has been reported to be a causative allergen of natto allergy. However, some of our patients with natto allergy were negative for PGA in the skin prick test (SPT). The sticky substance of natto beans contains a subtilisin family serine protease, nattokinase, along with PGA. In this study, we aimed to examine the antigenicity of nattokinase in natto allergy. METHODS: Eight patients, who developed symptoms after ingesting natto and positively reacted to natto (seven to the sticky substance in natto and one to the whole natto product) in their SPT, were enrolled in this study. To analyze IgE reactivity, we performed immunoblotting, ELISA, and SPT for natto (bean and sticky substance), and/or PGA, and/or nattokinase and/or cultured B. subtilis var. natto extract. RESULTS: In the SPT, four cases each were PGA-positive and PGA-negative. Immunoblotting of the sera from PGA-negative patients showed a protein band at 30 kDa, which was identified as nattokinase. Three PGA-negative cases, but not three PGA-positive cases, showed a positive reaction to nattokinase in the SPT and had a history of atopic dermatitis. The ELISA for nattokinase revealed a positive reaction of PGA-negative cases and negative reaction of PGA-positive cases in the SPT. CONCLUSIONS: We identified a subtilisin family serine protease, nattokinase, as a novel allergen in natto allergy patients unsensitized to PGA.

BACKGROUND: The Japanese baseline series (JBS), established in 1994, was updated in 2008 and 2015. The JBS 2015 is a modification of the thin-layer rapid-use epicutaneous (TRUE) test (SmartPractice Denmark, Hillerød, Denmark). No nationwide studies concerning the TRUE test have previously been reported. OBJECTIVES: To determine the prevalence of sensitizations to JBS 2015 allergens from 2015 to 2018. METHODS: We investigated JBS 2015 patch test results using the web-registered Skin Safety Care Information Network (SSCI-Net) from April 2015 to March 2019. RESULTS: Patch test results of 5865 patients were registered from 63 facilities. The five allergens with the highest positivity rates were gold sodium thiosulfate (GST; 25.7%), nickel sulfate (24.5%), urushiol (9.1%), p-phenylenediamine (PPD; 8.9%), and cobalt chloride (8.4%). The five allergens with the lowest positivity rates were mercaptobenzothiazole (0.8%), formaldehyde (0.9%), paraben mix (1.1%), mercapto mix (1.1%), and PPD black rubber mix (1.4%). CONCLUSIONS: Nickel sulfate and GST had the highest positivity rates. The JBS 2015, including a modified TRUE test, is suitable for baseline series patch testing.