HONEYBEE VENOM ALLERGY - RESULTS OF A STING CHALLENGE 1 YEAR AFTER STOPPING SUCCESSFUL VENOM IMMUNOTHERAPY IN 86 PATIENTS

In 86 patients with a history of severe systemic reactions (SRs) to honeybee stings confirmed by a positive skin test and/or RAST to honeybee venom (HBV), immunotherapy (IT) with HBV was stopped after 3 to 10 years. All patients had tolerated well a honeybee sting during IT and were resubmitted to a sting 1 year after VIT was stopped. At the latter time, 15 patients (17%) developed an SR and 71 did not. There was no difference between the two groups regarding age, sex, IT duration, severity of the SR before treatment, as well as diagnostic tests with HBV (skin tests, RAST, and specific IgG) before the challenge. Patients with a relapse of their allergy had, however, developed allergic SRs to IT injections more frequently than patients with lasting protection (p < 0.001). SRs to the sting challenge (CH) after IT was stopped occurred more frequently in those patients in whom efficacy of IT had previously been confirmed by lacking responses to a field sting than in patients who had tolerated an intentional CH during the injection period (p < 0.025). Indeed, the incidence of relapse after venom IT was stopped was only 9.6% in patients who had previously tolerated an intentional CH. It is concluded that well-tolerated HBV IT may be stopped after at least 3 years, provided its efficacy has been documented by a CH without SR.