Bee/Vespula Venom-Specific IgE Ratio Greater Than 5:1 Indicates Culprit Insect in Double-Sensitized Patients

Venom-allergic patients are frequently double-sensitized to honeybee venom (BV) and Vespula venom (VV). Genuine double allergy is uncommon.

To assess whether a quantitative comparison of BV- and VV-specific IgE levels permits an identification of the culprit venom in double-sensitized patients, and to evaluate whether independent sensitization to BV- and VV-specific components corresponds to an indication for double immunotherapy.

This single-center observational study evaluated 1,069 consecutive patients; 490 nonallergic controls were available for statistical comparison. The diagnosis (BV allergy, VV allergy, or double allergy) was based on a comprehensive allergological workup including patient history, IgE serology, intradermal skin test, and, when required, basophil activation testing. Quantitative allergen-specific IgE to BV, VV, rApi m 1, and rVes v 5 was retrospectively compared with the final diagnosis. The ratio of BV/VV-specific IgE levels was considered in double-sensitized venom-allergic patients.

Sensitization to whole-venom preparations and components was frequent in patients and asymptomatic controls, with higher specific IgE levels in the patient group. At least 5:1 dominance of the specific IgE to either BV or VV was documented in 239 of 459 double-sensitized venom-allergic patients (52.1%). Of these patients 232 (97.1%) received a diagnosis of monoallergy to only the venom to which they were dominantly sensitized.

Dominant specific IgE at a ratio of 5:1 indicates the culprit venom in double-sensitized allergic patients. Additional component-resolved diagnostic testing can be restricted to cases with double sensitization to whole venom at a ratio of less than 5:1. Double sensitization to rApi m 1 and rVes v 5 per se does not justify double venom immunotherapy.