Date Published: June 25, 2018
Publisher: Public Library of Science
Author(s): Pia Gattinger, Christian Lupinek, Lampros Kalogiros, Mira Silar, Mihaela Zidarn, Peter Korosec, Christine Koessler, Natalija Novak, Rudolf Valenta, Irene Mittermann, Edda Fiebiger.
Allergy to bee and wasp venom can lead to life-threatening systemic reactions. The identification of the culprit species is important for allergen-specific immunotherapy.
To determine a panel of recombinant bee and wasp allergens which is suitable for the identification of bee or wasp as culprit allergen sources and to search for molecular surrogates of clinical severity of sting reactions.
Sera from eighty-seven patients with a detailed documentation of their severity of sting reaction (Mueller grade) and who had been subjected to titrated skin testing with bee and wasp venom were analyzed for bee and wasp-specific IgE levels by ImmunoCAPTM. IgE-reactivity testing was performed using a comprehensive panel of recombinant bee and wasp venom allergens (rApi m 1, 2, 3, 4, 5 and 10; rVes v 1 and 5) by ISAC chip technology, ImmunoCAP and ELISA. IgG4 antibodies to rApi m 1 and rVes v 5 were determined by ELISA and IgE/IgG4 ratios were calculated. Results from skin testing, IgE serology and IgE/IgG4 ratios were compared with severity of sting reactions.
The panel of rApi m 1, rApi m 10, rVes v 1 and rVes v 5 allowed identification of the culprit venom in all but two of the 87 patients with good agreement to skin testing. Severities of sting reactions were not associated with results obtained by skin testing, venom-specific IgE levels or molecular diagnosis. Severe sting reactions were observed in patients showing < 1 ISU and < 2kUA/L of IgE to Api m 1 and/or Ves v 5. We identified a minimal panel of recombinant bee and wasp allergens for molecular diagnosis which may permit identification of bee and/or wasp as culprit insect in venom-sensitized subjects. The severity of sting reactions was not associated with parameters obtained by molecular diagnosis.
Systemic allergic reactions to insect venoms affect the skin, the respiratory and gastro-intestinal tract as well as the cardiovascular system and are often life-threatening. According to epidemiologic studies, it is estimated that approximately 1.2–3.5% of the population suffers from severe allergic reactions to insect venom allergens [1–4]. Venoms therefore belong to the most important elicitors of anaphylaxis in children and adults [5, 6]. Insects which most frequently cause severe allergic reactions belong to the order Hymenoptera. The family of Apidae (honeybee, Apis mellifera) and Vespidae (wasp; yellow jacket, Vespula vulgaris, Vespula germanica) and the paper wasp are among the most prevalent ones . Hymenoptera venoms contain a complex mixture of glycosylated and non-glycosylated proteins, peptides and also irritating substances such as enzymes, as well as biogenic amines. Allergen-specific immunotherapy (AIT) is extremely effective for the treatment of venom allergy  and shows long-term efficacy . Accurate diagnosis of the culprit insect is therefore important for selection of the right venom for AIT. More than 50% of the patients may show IgE double-positivity to bee and wasp venom , which can be due to genuine sensitisation to both venoms, cross-reactivity of IgE with homologous allergens in both venoms or cross-reactivity of IgE with clinically irrelevant carbohydrate epitopes . Evidence has been provided that molecular diagnosis with non-glycosylated recombinant bee and wasp allergens can facilitate the identification of the culprit venom because it eliminates cross-reactive carbohydrate epitopes [11–13]. However, several new bee and wasp allergens have been identified [14, 15]. While their contribution to increase the diagnostic sensitivity of bee and wasp venom allergy has been investigated, much less is known about their value for identifying the culprit sensitizing venom in double-sensitized patients [16–17]. Another important question is whether it is possible to establish surrogate markers similar as in the field of food allergy which allow prediction of the severity of allergic reactions on the basis of allergen-specific sensitivity, allergen-specific IgE levels and/or intensity of IgE recognition of certain marker allergens .
In this study we have addressed two aspects in the diagnosis of allergy to bee and wasp venom. The first aspect concerns the identification of the culprit insect for prescription of AIT. In fact, AIT of bee and wasp venom allergy is highly effective, but it is often very difficult to determine the culprit venom responsible for the allergic reaction in order to prescribe the correct venom for AIT. It has been shown that “false” positive test results can be obtained by allergen-extract based IgE serology due to the presence of clinically irrelevant cross-reactive carbohydrate epitopes in natural allergen extracts [10, 12, 30, 31]. Furthermore, it is known, that venom extracts contain toxic, pharmacologically active and irritating substances which may cause false positive skin test results . The use of pure recombinant allergen molecules from bee and wasp, which can be produced in a non-glycosylated form for IgE-serology, has been suggested as a possibility to discriminate between IgE sensitizations to bee and wasp [10–12]. The initial studies suggested that rApi m 1 from bee and rVes v 5 from wasp are suitable marker allergens to identify bee and wasp sensitized patients, respectively. However, several additional new bee and wasp allergens have then been characterized [14–16] and the question remained what panel of allergen molecules may be required for the discrimination between bee and wasp sensitization. Fig 5 displays a scheme of the currently available marker allergens for identifying genuine IgE sensitizations to bee (i.e., Api m 1, 3, 4 and 10) and wasp (i.e., Ves v 1 and 5) as well as of cross-reactive marker allergens (i.e., Api m 2 = Ves v 2; Api m 5 = Ves v 3). In this study we used rApi m 1, 2, 3, 4, 5 and 10 and Ves v 1 and 5 for IgE-based serology.