Inconsistent results of diagnostic tools hamper the differentiation between bee and vespid venom allergy

Abstract

Background: Double sensitization (DS) to bee and vespid venom is frequently observed in the diagnosis of hymenoptera venom allergy, but clinically relevant DS is rare. Therefore it is sophisticated to choose the relevant venom for specific immunotherapy and overtreatment with both venoms may occur. We aimed to compare currently available routine diagnostic tests as well as experimental tests to identify the most accurate diagnostic tool.

Methods: 117 patients with a history of a bee or vespid allergy were included in the study. Initially, IgE determination by the ImmunoCAP, by the Immulite, and by the ADVIA Centaur, as well as the intradermal test (IDT) and the basophil activation test (BAT) were performed. In 72 CAP double positive patients, individual IgE patterns were determined by western blot inhibition and component resolved diagnosis (CRD) with rApi m 1, nVes v 1, and nVes v 5.

Results: Among 117 patients, DS was observed in 63.7% by the Immulite, in 61.5% by the CAP, in 47.9% by the IDT, in 20.5% by the ADVIA, and in 17.1% by the BAT. In CAP double positive patients, western blot inhibition revealed CCD-based DS in 50.8%, and the CRD showed 41.7% of patients with true DS. Generally, agreement between the tests was only fair and inconsistent results were common.

Conclusion: BAT, CRD, and ADVIA showed a low rate of DS. However, the rate of DS is higher than expected by personal history, indicating that the matter of clinical relevance is still not solved even by novel tests. Furthermore, the lack of agreement between these tests makes it difficult to distinguish between bee and vespid venom allergy. At present, no routinely employed test can be regarded as gold standard to find the clinically relevant sensitization.

Figure 1. Frequency of double sensitization.

The rate of DS in 117 consecutive patients differed significantly (p<0.0001) and ranged from 17.1% with the BAT to 63.7% with the Immulite.

Figure 2. Frequency of double sensitization in supplemental tests in 72 CAP double positive patients.

n CRD: native component resolved diagnosis with nApi m 1, nVes v 1, nVes v 5. r/n CRD: combined component resolved diagnosis with recombinant rApi m 1, and native nVes v 1, nVes v 5. BAT (p = 0.324) and ADVIA (p = 0.874) showed a similar frequency of DS compared to WB inhibition and r/n CRD, although they were performed with native venom extracts.

Figure 3. Frequency of typical IgE patterns obtained by western blot inhibition in CAP double sensitized patients.

CCD: cross-reactive carbohydrate determinants, True DS: true double sensitization, WB: western blot, WB-I (western blot inhibition): To discriminate between IgE specific for peptide or carbohydrate epitopes, antibody binding to CCDs was inhibited by preincubating sera with MUXF-BSA. Among these patients the majority of DS was CCD-dependent. DS due to protein components of hyaluronidases played a minor role. n = 61.

Figure 4. Component resolved diagnosis in CAP double sensitized patients.

A Sensitization to bee and/or vespid venom in the component resolved diagnosis. Positive for bee venom: rApi m 1^pos / nVes v 1^neg and nVes v 5^neg; Positive for wasp venom: rApi m 1^neg / nVes v 1 and/or nVes v 5^pos; DS: rApi m 1^pos / nVes v 1 and/or nVes v 5^pos. n = 60. B Sensitization pattern in vespid venom allergic patients. The majority of patients were sensitized to both vespid major allergens (nVes v 1 and nVes v 5). Nevertheless, a considerable proportion had a mono sensitization to nVes v 1 or nVes v 5. n = 31.

Figure 5. Frequency of sensitization to bee and/or vespid venom in the basophil activation test.

n = 61.

Figure 6. BAT results in relation to western blot inhibition and component resolved diagnosis.

Although BAT was performed with native venom extracts, frequency of mono- and double sensitization was comparable with component based methods. Results of the BAT were in fair agreement with those of the CRD (60.0%, kappa 0.373, p<0001) and WB (59.6%, kappa 0.377, p<0001). Interestingly, the frequency of honey bee sensitization obtained with the CRD was markedly lower compared to BAT and WB, which could indicate a lower sensitivity of rApi m 1.

Figure 7. Determination of sIgE to MUXF (CCD) was not appropriate to distinguish between true and CCD-based double sensitization.

Patients with true DS in the WB (sensitization to major allergens or hyaluronidase) had detectable sIgE to MUXF and conversely, patients with a verified CCD-based DS by the WB inhibition had no detectable sIgE to MUXF. As the coincidence of true DS and detectable sIgE to MUXF was high, results could be misinterpreted and true DS could be easily overlooked.

Figure 8. Double positive results in CCD-dependent double sensitization.

CCD-dependent DS was verified with WB inhibition in 31 patients. The Immulite and IDT revealed the highest rates of DS in these patients (p<0.001; n = 24–31).