Gunter J. Sturm

Predictors of severe systemic anaphylactic reactions in patients with Hymenoptera venom allergy: Importance of baseline serum tryptase—a study of the European Academy of Allergology and Clinical Immunology Interest Group on Insect Venom Hypersensitivity

BACKGROUND Severe anaphylaxis to honeybee or vespid stings is associated with a variety of risk factors, which are poorly defined. OBJECTIVE Our aim was to evaluate the association of baseline serum tryptase concentrations and other variables routinely recorded during patient evaluation with the frequency of past severe anaphylaxis after a field sting. METHODS In this observational multicenter study, we enrolled 962 patients with established bee or vespid venom allergy who had a systemic reaction after a field sting. Data were collected on tryptase concentration, age, sex, culprit insect, cardiovascular medication, and the number of preceding minor systemic reactions before the index field sting. A severe reaction was defined as anaphylactic shock, loss of consciousness, or cardiopulmonary arrest. The index sting was defined as the hitherto first, most severe systemic field-sting reaction. Relative rates were calculated with generalized additive models. RESULTS Two hundred six (21.4%) patients had a severe anaphylactic reaction after a field sting. The frequency of this event increased significantly with higher tryptase concentrations (nonlinear association). Other factors significantly associated with severe reactions after a field sting were vespid venom allergy, older age, male sex, angiotensin-converting enzyme inhibitor medication, and 1 or more preceding field stings with a less severe systemic reaction. CONCLUSION In patients with honeybee or vespid venom allergy, baseline serum tryptase concentrations are associated with the risk for severe anaphylactic reactions. Preventive measures should include substitution of angiotensin-converting enzyme inhibitors.

Predictors of side effects during the buildup phase of venom immunotherapy for Hymenoptera venom allergy: the importance of baseline serum tryptase.

BACKGROUND Severe side effects during venom immunotherapy (VIT) are associated with a variety of risk factors. OBJECTIVE Our aim was to evaluate the association of baseline serum tryptase concentration (BTC) and of other parameters, which are routinely recorded during patient evaluation, with the frequency of severe reactions requiring an emergency intervention during the buildup phase of VIT. METHODS In this observational prospective multicenter study, we enrolled 680 patients with established honeybee or vespid venom allergy who underwent VIT. Data were collected on tryptase concentration, age, sex, culprit insect, cardiovascular medication, degree of preceding sting reaction, preventive antiallergic medication before therapy, time between last preceding sting reaction and VIT, venom specific IgE concentration, and type of buildup procedure. Relative rates were calculated with generalized additive models. RESULTS Fifty-seven patients (8.4%) required an emergency intervention during buildup because of a severe systemic reaction. The frequency of interventions increased significantly with higher BTC (log-linear association; adjusted odds ratio, 1.56; 95% CI, 1.15-2.11; P < .005). The predictive power of BTC was markedly greater when VIT was performed for vespid venom allergy than for bee venom (for bee VIT, no significant association; for vespid VIT, log-linear association; adjusted odds ratio, 2.33; 95% CI, 1.28-4.26; P = .005). The most important other factor significantly associated with severe reactions during the buildup phase of VIT was bee venom allergy. CONCLUSION Before vespid VIT, measurement of baseline serum tryptase concentration should be used to identify patients with a high risk for side effects. Patients with bee venom allergy require a particularly high degree of surveillance during VIT.

The CD63 basophil activation test in Hymenoptera venom allergy: a prospective study

Background:  The basophil activation test (BAT), which relies on flow cytometric quantitation of the allergen‐induced up‐regulation of the granule‐associated marker CD63 in peripheral blood basophils, has been suggested to be a useful approach in detecting responsiveness to allergens. The purpose of this study was to establish the usefulness of the BAT with regard to the clinical history and current diagnostic tools in Hymenoptera venom allergy using a prospective study design.

11-Dehydro-thromboxane B2, a stable thromboxane metabolite, is a full agonist of chemoattractant receptor-homologous molecule expressed on TH2 cells (CRTH2) in human eosinophils and basophils.

Thromboxane (TX) A2, a cyclooxygenase-derived mediator involved in allergic responses, is rapidly converted in vivo to a stable metabolite, 11-dehydro-TXB2, which is considered to be biologically inactive. In this study, we found that 11-dehydro-TXB2, but not the TXA2 analogue U46,619 or TXB2, activated eosinophils and basophils, as assayed by flow cytometric shape change. 11-Dehydro-TXB2 was also chemotactic for eosinophils but did not induce, nor inhibit, platelet aggregation. Chemoattractant receptor-homologous molecule expressed on TH2 cells (CRTH2) is an important chemoattractant receptor expressed by eosinophils, basophils, and TH2 lymphocytes, and prostaglandin (PG)D2 has been shown to be its principal ligand. 11-Dehydro-TXB2 induced calcium flux mainly from intracellular stores in eosinophils, and this response was desensitized after stimulation with PGD2 but not other eosinophil chemoattractants. Shape change responses of eosinophils and basophils to 11-dehydro-TXB2 were inhibited by the thromboxane (TP)/CRTH2 receptor antagonist ramatroban, but not the selective TP antagonist SQ29,548, and were insensitive to pertussis toxin. The phospholipase C inhibitor U73,122 attenuated both 11-dehydro-TXB2- and PGD2-induced shape change. 11-Dehydro-TXB2 also induced the chemotaxis of BaF/3 cells transfected with hCRTH2 but not naive BaF/3 cells. At a threshold concentration, 11-dehydro-TXB2 had no antagonistic effect on CRTH2-mediated responses as induced by PGD2. These data show that 11-dehydro-TXB2 is a full agonist of the CRTH2 receptor and hence might cause CRTH2 activation in cellular contexts where PGD-synthase is not present. Given its production in the allergic lung, antagonism of the 11-dehydro-TXB2/CRTH2axis may be of therapeutic relevance.

Prostaglandin E2 Inhibits Eosinophil Trafficking through E-Prostanoid 2 Receptors

The accumulation of eosinophils in lung tissue is a hallmark of asthma, and it is believed that eosinophils play a crucial pathogenic role in allergic inflammation. Prostaglandin (PG) E2 exerts anti-inflammatory and bronchoprotective mechanisms in asthma, but the underlying mechanisms have remained unclear. In this study we show that PGE2 potently inhibits the chemotaxis of purified human eosinophils toward eotaxin, PGD2, and C5a. Activated monocytes similarly attenuated eosinophil migration, and this was reversed after pretreatment of the monocytes with a cyclooxygenase inhibitor. The selective E-prostanoid (EP) 2 receptor agonist butaprost mimicked the inhibitory effect of PGE2 on eosinophil migration, whereas an EP2 antagonist completely prevented this effect. Butaprost, and also PGE2, inhibited the C5a-induced degranulation of eosinophils. Moreover, selective kinase inhibitors revealed that the inhibitory effect of PGE2 on eosinophil migration depended upon activation of PI3K and protein kinase C, but not cAMP. In animal models, the EP2 agonist butaprost inhibited the rapid mobilization of eosinophils from bone marrow of the in situ perfused guinea pig hind limb and prevented the allergen-induced bronchial accumulation of eosinophils in OVA-sensitized mice. Immunostaining showed that human eosinophils express EP2 receptors and that EP2 receptor expression in the murine lungs is prominent in airway epithelium and, after allergen challenge, in peribronchial infiltrating leukocytes. In summary, these data show that EP2 receptor agonists potently inhibit eosinophil trafficking and activation and might hence be a useful therapeutic option in eosinophilic diseases.

Clinical contraindications to allergen immunotherapy: An EAACI position paper

Clinical indications for allergen immunotherapy (AIT) in respiratory and Hymenoptera venom allergy are well established; however, clinical contraindications to AIT are not always well documented. There are some discrepancies when classifying clinical contraindications for different forms of AIT as ‘absolute’ or ‘relative’. EAACI Task Force on ‘Contraindications to AIT’ was created to evaluate and review current literature on clinical contraindications, and to update recommendations for both sublingual and subcutaneous AIT for respiratory and venom immunotherapy. An extensive review of the literature was performed on the use of AIT in asthma, autoimmune disorders, malignant neoplasias, cardiovascular diseases, acquired immunodeficiencies and other chronic diseases (including mental disorders), in patients treated with β‐blockers, ACE inhibitors or monoamine oxidase inhibitors, in children under 5 years of age, during pregnancy and in patients with poor compliance. Each topic was addressed by the following three questions: (1) Are there any negative effects of AIT on this concomitant condition/disease? (2) Are more frequent or more severe AIT‐related side‐effects expected? and (3) Is AIT expected to be less efficacious? The evidence, for the evaluation of these clinical conditions as contraindications, was limited, and most of the conclusions were based on case reports. Based on an extended literature research, recommendations for each medical condition assessed are provided. The final decision on the administration of AIT should be based on individual evaluation of any medical condition and a risk/benefit assessment for each patient.

The basophil activation test in the diagnosis of allergy: technical issues and critical factors.

Background:  The basophil activation test (BAT) is a widely validated and reliable tool especially for the diagnosis of hymenoptera venom allergy. Nevertheless, several pitfalls have to be considered and outcomes may differ because of diverse in‐house protocols and commercially available kits. We aimed to identify the factors that may influence results of the CD63‐based BAT.

Detection of IgE to recombinant Api m 1 and rVes v 5 is valuable but not sufficient to distinguish bee from wasp venom allergy

To the Editor: Hofmann et al tackle an important problem in Hymenoptera venom allergy: the frequently observed (asymptomatic) double sensitization to bee andwasp venom, and the problemof identifying the relevant venom for immunotherapy. Component-resolved diagnosis is undoubtedly a major advancement in the diagnosis of Hymenoptera venom allergy. Nevertheless, the following aspects should be noted: Hofmann et al aswell asM€uller et al enrolled patients on the basis of a positive skin test response. However, some patients with a venom allergy have negative skin tests. Golden et al frequently observed negative skin tests in patients with allergy toHymenoptera venom, and a considerable number of these patients reacted to sting challenges. Particularly, a low total IgE level is linked to negative skin tests and nondetectable specific IgE (sIgE) but is associated with more severe reactions. Therefore, patients at high risk could bemissed. Second, the low frequency of sensitization to recombinant (r) Api m 1 compared with the bee venom extract is a cause for concern. Initially, a prevalence of sIgE to rApi m 1 of 97% with the ADVIA system (Siemens, Tarrytown, NY) was reported, but Hofmann et al registered a frequency of only 79% for the ImmunoCAP assay (Phadia, Uppsala, Sweden). We rechecked the sensitivity of sIgE to bee venom extract and rApi m1 in the same system. The data fromHofmann et al could be confirmed at 2Austrian centers,where positive skin testswereused as inclusion criterion. However, an even lower frequency of sensitization to rApi m 1 was registered at 1 Austrian center when all patients with systemic sting reactions in the past were included (Table I). Furthermore, regional differences in sensitization patterns have to be taken into account. In Europe, approximately two thirds of patients with allergy to Hymenoptera venom react towasp stings and only one third to bee stings. By contrast, IgE determination reveals double-positive results in up to 59%of patients. Thus, a diagnostic tool is urgently needed to exclude cross-reactivity via cross-reactive carbohydrate determinants. Because wasp venom allergies are more frequent, and bee venom bears more cross-reactive carbohydrate determinants, typically nonspecific cross-reactions to bee venom must be excluded. Is it adequate merely to determine Api m 1 for this purpose? In the worst case, 38 of 100 patients with bee venom allergy will not be diagnosed by sIgE to rApi m 1, as shown in Table I. Why is this so? Given the limited availability of the substances, we randomly analyzed 40 sera from the low-sensitivity group regarding sIgE to bee venom hyaluronidase (rApi m 2) andmelittin (native [n]Apim 4)with research prototype ImmunoCAPassays.All but 1 patient had detectable sIgE to beevenomextract, whereas 13 patients (32.5%) could not be diagnosed with rApi m 1 alone. After the use of rApi m 2 and nApi m 4, 6 additional patients could be diagnosed, and only 7 (17.5%) remained negative. In detail, 5 patients had detectable sIgE to rApi m 2 and 1 putatively to nApi m 4 only. Generally, 65.0% of patients were sensitized to rApi m 1, 52.2% to rApi m 2, and 42.5% to nApi m 4. From these data, it can be assumed that sensitization to multiple allergens might be common. Furthermore, we could again confirm the clinical relevance of Api m 2 beyond its carbohydrate epitopes. Therefore, these preliminary results indicate that a genuine bee venom sensitization can most likely be excluded in cases of negative sIgE test results to at least Api m 1 and 2.Nevertheless, addition of beevenomallergens likeApim3, 4, 5, 6, and 10would further increase diagnostic accuracy.A similar approach might be valid to exclude genuine wasp venom sensitization: because up to 13% of patients with wasp venom allergy could be missed, the combined determination of sIgE to Ves v 1 and 5 is essential. Taken together, the data indicate that the suggested approach of using rApi m 1 and rVes v 5 is insufficient and even fraught with risk for some patients because genuine sensitization to other major allergens might be missed. Gunter J. Sturm, MD Wolfgang Hemmer, PhD Thomas Hawranek, MD Roland Lang, PhD Markus Ollert, MD Edzard Spillner, PhD Simon Blank, PhD Danijela Bokanovic, MD Werner Aberer, MD

CD203c‐based basophil activation test in allergy diagnosis: Characteristics and differences to CD63 upregulation

The basophil activation test (BAT) based on CD203c upregulation has been validated as a reliable tool for the diagnosis of IgE‐mediated allergies. Nevertheless, CD203c‐based BAT is hardly comparable with that of CD63‐based tests, as the mechanisms of CD203c versus CD63 induction differ considerably. The aim of the present study was to identify potent influencing factors of the CD203c‐based BAT and to emphasize differences between CD63 and CD203c detection.

Inconsistent Results of Diagnostic Tools Hamper the Differentiation between Bee and Vespid Venom Allergy

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.