Sublingual Immunotherapy With Honeybee Venom Is Effective In Patients With Large Local Reactions Due To Bee Sting. A Randomised, Double Blind Placebo Controlled Trial

Hymenoptera venom immunotherapy confers protection against hymenoptera sting, and effectiveness of VIT can be demonstrated by reduction of size of large local reactions. Venom immunotherapy is given by injections, but sublingual immunotherapy (SI) proved effective in respiratory allergy, thus its use in hymenoptera allergy can be hypothesized. We evaluated efficacy of SI with honeybee venom assessing effect on large local reactions under controlled sting challenges. This is a randomised, double blind, placebo controlled study. Patients with only LLR and single sensitisation to honeybee were enrolled. After baseline sting challenge and blood sampling they were randomised receiving SI (15 patients) or placebo (15 patients) for 6 months. Treatment (Anallergo, Italy) involved a 6-week build-up, followed by a maintenance phase with 525 mcg venom were given monthly. Controlled sting challenge was repeated after 6 months of treatment. 30 patients (18 male, mean 44,5 yrs) were enrolled and 26 completed the study, with 1 dropout in the active and 3 dropouts in the placebo group. In active group the median peak diameter decreased from 20.5 to 8.5 cm (p= 0.014), whereas no change was seen in placebo group (23.0 vs 20.5 cm; p= NS). Diameter was reduced >50% in 8/14 (57%) patients. One systemic reaction (generalized urticaria) occurred in a placebo patient on sting challenge. HB-SLIT significantly reduced extent of LLR in HB allergic subjects, and its safety profile was satisfactory. This study suggests feasibility of SLIT in hymenoptera allergy. Dose-ranging studies and trials in patients with systemic reactions should be next step to confirm our observations.