IgE to recombinant allergens Api m 1, Ves v 1, and Ves v 5 distinguish double sensitization from crossreaction in venom allergy

Background Diagnostic tests in patients with Hymenoptera venom allergy are frequently positive to venoms of both honey bee and wasp (Vespula). Component-resolved analysis with recombinant species-specific major allergens (rSSMA) may help to distinguish true double sensitization from crossreactivity. Methods Included were 121 patients with systemic allergic reactions to Hymenoptera stings, 76 with double positivity of serum-specific IgE (sIgE) to both venoms, 45 with single positivity to bee or wasp venom, and 32 controls without history of systemic reactions to Hymenoptera stings and no sIgE to whole venoms. In venom-allergic patients and controls, sIgE to rSSMA Api m 1 of bee venom and to Ves v 1 and Ves v 5 of wasp venom were tested by ImmunoCAP. Results Only 47% of 76 patients with double positivity to whole venoms reacted also to rSSMA of both species. Specificity of sIgE to the 3 rSSMA was very high, with no sIgE to rSSMA of the other species in single-positive venom-allergic patients and only one control with low sIgE to Ves v 1. All wasp-allergic single-positive patients had sIgE to Ves v 5 and/or Ves v 1, and 78.3% of single-positive bee venomallergic patients had sIgE to Api m 1. Conclusion Specificity of sIgE to rSSMA of both species is excellent. Sensitivity of sIgE to rSSMA was optimal for wasp venom. Sensitivity of bee venom Api m 1 could be increased by adding rSSMA of other important bee venom allergens.