Immunotherapy with commercial venoms is efficacious for anaphylactic reactions to Vespa orientalis stings.

Background: Vespa orientalis (VO) stings occasionally induce anaphylaxis. In the absence of commercial VO venom, allergists use commercial venoms for immunotherapy, despite having no indication regarding efficacy. We attempted to examine the effectiveness of immunotherapy with commercial venoms in patients with VO allergy and to identify the venom accountable for this effect.

Methods: Patients who unequivocally identified VO as the culprit insect were administered venom immunotherapy with the commercial venoms available in Israel to which they had positive skin tests. Patients were also skin tested with VO venom sac extracts and, after reaching the maintenance dose, were sting challenged by a live insect. The allergenic components in the venom were determined by immunoblotting.

Results: Twelve patients were recruited and, based on their skin test results, all were treated with yellow jacket (YJ) venom, either alone or combined with other venoms. All 8 patients who were sting challenged by VO demonstrated positive skin test responses to VO venom. Six of the stung patients tolerated the sting challenge uneventfully. Two patients developed minimal transient symptoms that resolved spontaneously. SDS-PAGE with patient sera suggested cross-reactivity between VO and YJ venoms at molecular weights of 39-42 kDa. Using phospholipases, antigen 5 and hyaluronidase derived from several Vespa, Dolichovespula and Vespula species, hyaluronidase is possibly accountable for inducing the allergic reaction.

Conclusion: In the absence of commercial VO venom the practice of treating patients allergic to this insect with available commercial venoms seems to be efficacious and YJ venom is probably responsible for this effect.