Case report of venom immunotherapy for a patient with large local reactions

Background: Inadvertent Hymenoptera stings reportedly elicit large local reactions in up to 17% of the general population. Current practice parameters do not recommend venom immunotherapy (IT) for these cases. Objective: The goal of this case study was to investigate the clinical and immunologic consequences of venom IT in a newly sensitized individual with large local reactions using an intentional sting challenge before and after treatment to document changes in reaction severity. Methods: A 47-year-old man became honeybee venom (HBV)-allergic with progressively larger reactions at honeybee sting sites with subsequent stings. Then, a sting on his forefinger produced a large (62 cm) local reaction with swelling throughout the arm that persisted for more than 4 weeks with severe pain. He refused steroid therapy and voluntarily requested venom IT with honeybee-sting challenges to monitor clinical parameters and immunologic changes in his skin and serum before and 7 months post-HBV maintenance IT. Results: A single pre-IT bee sting challenge produced an 11.4-cm wheal with 13-cm erythema at the sting site after 15 minutes, followed by several weeks of edema that involved the entire arm. After rapid escalation of venom IT to maintenance in 7 weeks, a post-maintenance IT sting challenge with two honeybees produced a 3-cm diameter erythema with no wheal at 15 minutes and no late-phase induration. Complete loss of any visible reaction at the field sting site resulted after 13 months of maintenance venom IT. A HBV-specific IgG antibody level >3.5 μg/mL and IgG/IgE antibody molar ratio >500 persisted over the period of venom IT, with venom skin reactivity diminishing 100-fold. Conclusions: These results support venom IT use in the treatment of Hymenoptera venom-sensitive individuals who experience large local reactions and are at risk for repetitive inadvertent stings.