Evaluation and validation of a bee venom sting challenge performed by a micro-syringe.

Background: The honeybee sting challenge is considered a reliable procedure to evaluate the efficacy of specific immunotherapy, but it is difficult and unpractical to perform in clinical practice, because live insects are required.

Objective: To assess the feasibility and reliability of a challenge test using a micro-syringe, and compared the procedure with sting challenge.

Methods: Patients on bee venom immunotherapy and without systemic reactions at field sting were enrolled. They underwent a sting challenge with live bee, and large local reactions were assessed up to 48 hours. Those patients displaying systemic reactions at the sting challenge were excluded from the syringe challenge for ethical reasons. The syringe challenge was done by injecting 0.5 μL fresh unfiltered bee venom at 2 mm depth (the length of the sting left by a bee). The same follow-up as at the first challenge was performed. Bee-specific immunoglobulin E (IgE) and tryptase were measured after each challenge.

Results: Nineteen patients underwent the sting challenge with live bees. Four had immediate systemic reactions (urticaria or asthma) and were excluded from the second challenge. The remaining 15 patients with large local reaction underwent the syringe challenge. No significant difference was seen in the maximum area of the large local reactions between the challenge with live bees and the syringe challenge. Also, no change was seen in tryptase and specific antibodies.

Conclusion: This preliminary study suggests that the micro-syringe challenge with honeybee venom is feasible and produces results indistinguishable from those of the traditional sting challenge.