Clinical significance of a basophil activation test for Japanese beekeepers naturally sensitized to honey bee venom.

Background: The basophil activation test (BAT) has high sensitivity and specificity for diagnosing Hymenoptera venom allergy and is useful for predicting the clinical sensitivity of bee venom-allergic patients after venom immunotherapy. Patients sensitized to Hymenoptera venom are at risk for systemic reactions (SRs) to subsequent stings. Therefore, a tool that can predict the occurrence of SRs and the severity of Hymenoptera stings is needed.

Objective: We performed BATs on Japanese beekeepers naturally sensitized to honey bee venom (HBV) and analyzed the positive threshold concentration for the occurrence of SRs following honey bee stings (HBS).

Methods: Sixty-one beekeepers were interviewed and blood samples were taken. Data including history of HBS and the occurrence and severity of SRs to HBS were recorded. Blood samples were exposed to HBV-specific IgE antibodies (sIgE) and BAT was performed. Participants with HBV-sIgE ≥ class 1 were considered sensitized to HBV. The positive threshold for BAT scored as 0.0001, 0.001, 0.01, 0.1, and 1 μg/ml was classified as classes 5, 4, 3, 2, and 1, respectively. Samples negative at 1 μg/ml were classified as class 0.

Results: About 40% of beekeepers with a positive BAT threshold ≤ 0.1 μg/ml had SRs after HBS. The mean score of the BAT positivity threshold for beekeepers who developed SRs was significantly lower than that for beekeepers with no history of SRs (2.6 ± 0.8 vs 1.4 ± 1.1, P < 0.01).

Conclusion: Analysis of the positive threshold of BAT in Japanese beekeepers naturally sensitized to HBV may be a useful tool for predicting the occurrence of SRs.