Sublingual immunotherapy for large local reactions caused by honeybee sting: a double-blind, placebo-controlled trial.

Background: Sublingual immunotherapy (SLIT) proved effective and safe in respiratory allergy, and thus its use in hymenoptera allergy can be hypothesized.

Objective: We sought to assess, in a proof-of-concept study, whether SLIT might potentially be beneficial in hymenoptera allergy. The sting challenge in large local reactions (LLRs) was used to test this hypothesis.

Methods: We performed a randomized, double-blind, placebo-controlled study involving patients with LLRs who were monosensitized to honeybee. After the baseline sting challenge, they were randomized to either SLIT or placebo for 6 months. The treatment (Anallergo, Florence, Italy) involved a 6-week build-up period, followed by maintenance with 525 microg of venom monthly. The sting challenge was repeated after 6 months.

Results: Thirty patients (18 male patients; mean age, 44.5 years) were enrolled, and 26 completed the study, with 1 dropout in the active group and 3 dropouts in the placebo group. In the active group the median of the peak maximal diameter of the LLRs decreased from 20.5 to 8.5 cm (P = .014), whereas no change was seen in the placebo group (23.0 vs 20.5 cm, P = not significant). The diameter was reduced more than 50% in 57% of patients. One case of generalized urticaria occurred in a placebo-treated patient at sting challenge. No adverse event caused by SLIT was reported.

Conclusion: Honeybee SLIT significantly reduced the extent of LLRs, and its safety profile was good. Although LLRs are not an indication for immunotherapy, this proof-of-concept study suggests that SLIT in hymenoptera allergy deserves further investigation. Trials involving systemic reactions and dose-ranging studies are needed.