Abstract
Allergic reactions to Hymenoptera venom, which could lead to systemic and even fatal symptoms, is characterized by hypersensitivity reactions mediated by specific IgE (sIgE) driven to venom allergens. Patients multisensitized to sIgE usually recognize more than one allergen in different Hymenoptera species. However, the presence of sIgE directed against Cross-Reactive Carbohydrate Determinant (CCD), which occurs in some allergens from Hymenoptera venom, hampers the identification of the culprit insects. CCD is also present in plants, pollen, fruits, but not in mammals. Bromelain (Brl) extracted from pineapples is a glycoprotein commonly used for reference to sIgE-CCD detection and analysis. In sera of fifty-one Hymenoptera allergic patients with specific IgE ≥ 1.0 KU/L, we assessed by immunoblotting the reactivity of sIgE to the major allergens of Apis mellifera, Polybia paulista and Solenopsis invicta venoms. We also distinguished, using sera adsorption procedures, the cases of CCD cross-reaction using Brl as a marker and inhibitor of CCD epitopes. The presence of reactivity for bromelain (24–28 kDa) was obtained in 43% of the patients, in which 64% presented reactivity for more than one Hymenoptera venom in radioallergosorbent (RAST) tests, and 90% showed reactivity in immunoblot analysis to the major allergens of Apis mellifera, Polybia paulista and Solenopsis invicta venoms. Sera adsorption procedures with Brl lead to a significant reduction in patients’ sera reactivity to the Hymenoptera allergens. Immunoblotting assay using pre- and post-Brl adsorption sera from wasp-allergic patients blotted with non-glycosylated recombinant antigens (rPoly p1, rPoly p5) from Polybia paulista wasp venom showed no change in reactivity pattern of sIgE that recognize allergen peptide epitopes. Our results, using Brl as a marker and CCD inhibitor to test sIgE reactivity, suggest that it could complement diagnostic methods and help to differentiate specific reactivity to allergens’ peptide epitopes from cross-reactivity caused by CCD, which is extremely useful in clinical practice.
Highlights
Allergic reaction to insect venom is one of the most common causes of anaphylaxis [1] and may occur in up to 42% of accident cases [2]
Key Contribution: Bromelain can be used as a marker and cross-reactive carbohydrate determinants (CCD) inhibitor to supplement diagnostic methods and help to differentiate clinical cases with cross-reactivity caused by CCD, being useful and promoting improvement in diagnostic and clinical practice
Sera from sensitized patients may present multiple reactivities (30–50%) and cross-react with another Hymenoptera venom (60–70%) [7,8]. These reactions may occur due to several factors such as elevated specific immunoglobulin E (IgE) levels, independent of the sensitization to each venom; IgE antibodies with cross-reactivity against homologous proteins present in venoms or by the binding of IgE antibodies to cross-reactive carbohydrate determinants (CCD) [9,10,11]
Summary
Allergic reaction to insect venom is one of the most common causes of anaphylaxis [1] and may occur in up to 42% of accident cases [2]. Accidents with the stings of these insects cause symptoms such as pain, itching and swelling in all cases, and, in some allergic patients, specific reactions are observed as exuberant local reactions, systemic reactions and fatal reactions [6]. Sera from sensitized patients may present multiple reactivities (30–50%) and cross-react with another Hymenoptera venom (60–70%) [7,8] These reactions may occur due to several factors such as elevated specific IgE levels, independent of the sensitization to each venom; IgE antibodies with cross-reactivity against homologous proteins present in venoms or by the binding of IgE antibodies to cross-reactive carbohydrate determinants (CCD) [9,10,11]
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