The sting challenge test in Hymenoptera venom allergy. Position paper of the Subcommittee on Insect Venom Allergy of the European Academy of Allergology and Clinical Immunology

Global View on Ant Venom Allergy: from Allergenic Components to Clinical Management

Hymenoptera venom allergy is characterised by systemic anaphylactic reactions that occur in response to stings from members of the Hymenoptera order. Stinging by social Hymenoptera such as ants, honeybees, and vespids is one of the 3 major causes of anaphylaxis; along with food and drug exposure, it accounts for up to 43% of anaphylaxis cases and 20% of anaphylaxis-related fatalities. Despite their recognition as being of considerable public health significance, stinging ant venoms are relatively unexplored in comparison to other animal venoms and may be overlooked as a cause of venom allergy. Indeed, the venoms of stinging ants may be the most common cause of anaphylaxis in ant endemic areas. A better understanding of the natural history of venom allergy caused by stinging ants, their venom components, and the management of ant venom allergy is therefore required. This article provides a global view on allergic reactions to the venoms of stinging ants and the contemporary approach to diagnose and manage ant venom allergy.

Impact of specific immunotherapy and sting challenge on the quality of life in patients with hymenoptera venom allergy

Background

An experienced life-threating anaphylactic reaction to hymenoptera venom can sustainably impair patients’ quality of life (QoL). Besides carrying emergency medication, venom-specific immunotherapy (VIT) exists as a causal treatment of allergy.

Objective

This study aimed to examine QoL, anxiety, depression, and physical and mental health in patients allergic to hymenoptera venom before and during VIT and the impact of a tolerated sting challenge (SC).

Methods

Between July 2017 and August 2017, 142 patients with venom allergy were analyzed using validated questionnaires as the: Vespid Allergy Quality for Life Questionnaire" (VQLQ-d), the "Hospital Anxiety and Depression Scale" (HADS-D) and the "Short Form 36" (SF-36). To evaluate the impact of VIT and SC on the QoL, patients were divided into 3 groups: (A) VIT and tolerated SC (n = 45), (B) VIT before carrying out SC (n = 73), and (C) therapy-naïve before VIT (n = 20). Further parameters like gender, age, insect species, and severity of the anaphylactic reaction were assessed.

Results

A significant correlation between the health-related QoL and the parameters of gender and state of treatment was seen. Especially male patients, as well as patients allergic to yellow jacket venom, benefit from a SC in terms of a significant increase in their QoL. In the total study cohort, a clear trend was observed towards a higher QoL in patients under VIT who tolerated a SC. Overall, neither the patients’ age nor the insect species exerted a relevant influence on QoL, depression or anxiety. However, women showed a lower QoL combined with higher anxiety and depression scores than men.

Conclusion

Immunotherapy leads to an improved QoL, which can be further increased by a SC. A tolerated SC conceivably reassures the patients by objectifying the treatment success. Female patients appear to have a stronger impaired QoL per se. Taken together, a SC can be performed during VIT to strengthen the patients’ QoL.

Benefits and limitations of sting challenge in hymenoptera venom allergy

The prevalence of systemic reactions to hymenoptera stings is up to 7.5%. Venom-specific immunotherapy (VIT) is an established treatment for insect venom allergy. In order to monitor the allergic status and thus the success of the therapy, controlled sting challenge under VIT continues to be the gold standard. This review deals not only with useful indications and therapeutic consequences but also with critical aspects that should be considered when performing sting challenge.

Precision Medicine in Hymenoptera Venom Allergy: Diagnostics, Biomarkers, and Therapy of Different Endotypes and Phenotypes

Allergic reactions to stings of Hymenoptera species may be severe and are potentially fatal deviations of the immunological response observed in healthy individuals. However, venom-specific immunotherapy (VIT) is an immunomodulatory approach able to cure venom allergy in the majority of affected patients. An appropriate therapeutic intervention and the efficacy of VIT not only depend on a conclusive diagnosis, but might also be influenced by the patient-specific manifestation of the disease. As with other diseases, it should be borne in mind that there are different endotypes and phenotypes of venom allergy, each of which require a patient-tailored disease management and treatment scheme. Reviewed here are different endotypes of sting reactions such as IgE-mediated allergy, asymptomatic sensitization or a simultaneous presence of venom allergy and mast cell disorders including particular considerations for diagnosis and therapy. Additionally, phenotypical manifestations of venom allergy, as e.g. differences in age of onset and disease severity, multiple sensitization or patients unsusceptible to therapy, are described. Moreover, biomarkers and diagnostic strategies that might reflect the immunological status of the patient and their value for therapeutic guidance are discussed. Taken together, the increasing knowledge of different disease manifestations in venom hypersensitivity and the growing availability of diagnostic tools open new options for the classification of venom allergy and, hence, for personalized medical approaches and precision medicine in Hymenoptera venom allergy.

Safety and Effectiveness of a 3-Day Rush Insect Venom Immunotherapy Protocol

BACKGROUND

Venom immunotherapy (VIT) is an established and effective treatment for patients with Hymenoptera venom allergies. Especially during the build-up of VIT, systemic allergic reactions are a key issue.

OBJECTIVE

To investigate the safety and effectiveness of a 3-day rush insect VIT protocol and a strategy for the management of individuals with VIT-induced anaphylaxis.

METHODS

In this retrospective monocentric study, 11-year data regarding build-up cycles of VIT were retrieved from institutional records. The following parameters of VIT-induced anaphylaxis were analyzed: frequency, severity, time of occurrence within the build-up cycle, and impact on the success of VIT. The effectiveness of VIT was assessed by the results of sting challenges (SCs) by the culprit insect.

RESULTS

In total, 1,317 initial build-up cycles of VIT were evaluated in this study, and the frequency of VIT-induced anaphylaxis was 6.6%. Anaphylaxis occurred most frequently when the daily cumulative venom dose was ≥100 µg. A group (n = 65) of patients with VIT-induced anaphylaxis in this dose range temporarily received a reduced maintenance dose, and without additional co-medications or complications, the target dose was reached after a second build-up in 91% of the cycles. After completing the VIT build-up, SCs were performed in 76.9% of the cohort, and the effectiveness of VIT was confirmed by 98.5% of the tests.

CONCLUSIONS

In this study, we report a 3-day VIT rush protocol with a reasonable rate of VIT-induced anaphylaxis and excellent effectiveness of VIT.

Venom allergy treatment practices in Poland in comparison to guidelines: next edition of the national audit

Introduction

Venom immunotherapy treatment (VIT) is the only causal treatment of hymenoptera venom anaphylaxis, which aims to provide long-lasting immunoprotection against severe reactions to subsequent stings.

Aim

To reassess the compliance of VIT procedures in the Polish allergy centres with the European guidelines.

Material and methods

A structured questionnaire survey conducted in all 33 VIT-centres. The response rate was 94%.

Results

The ultrarush initial protocol was the most common protocol (71%, n = 22), usually lasting for 3.5 h (50%, n = 7). The most frequent (36%, n = 11) time interval from the initial to the first maintenance dose (MD) was 14 days, ranging from 7 to 35 days. All centres used an MD of 100 μg. The most frequent time interval between subsequent MDs was 4 weeks (58%, n = 18). Five years’ of VIT was declared by 71% (n = 22). Before the termination of treatment, more than half of the centres (58%, n = 18) performed sIgE and almost half (42%, n = 13) performed skin tests. To confirm VIT efficacy, few centres (26%, n = 8) conducted the sting challenge. About half of centres provided the patients with an adrenalin auto-injector both at the time of initial diagnostics and at the end of treatment. More than half (55%, n = 17) used antihistamines in all patients. Almost half (45%, n = 14) declared to stop treatment with β-blockers and almost one fourth (23%, n = 7) discontinued angiotensin-converting-enzyme inhibitors.

Conclusions

In the most important procedures, there is a very high compliance with the guidelines. In the areas where the guidelines are not precise, we observed a large spread of results.

Immunological differences between insect venom-allergic patients with and without immunotherapy and asymptomatically sensitized subjects

BACKGROUND

Currently available tests are unable to distinguish between asymptomatic sensitization and clinically relevant Hymenoptera venom allergy. A reliable serological marker to monitor venom immunotherapy (VIT) does also not exist. Our aim was to find reliable serological markers to predict tolerance to bee and vespid stings.

METHODS

We included 77 asymptomatically sensitized subjects, 85 allergic patients with acute systemic sting reactions, and 61 allergic patients currently treated with VIT. Levels of sIgE and sIgG₄ to bee and vespid venom, rApi m 1, and rVes v 5 were measured immediately after allergic sting reactions or before sting challenges and 4 weeks later. All sting challenges were tolerated. The inhibitory activity was determined using BAT inhibition and ELIFAB assay.

RESULTS

Median sIgG₄ levels were 96-fold higher in VIT patients (P < .001) while sIgE/sIgG₄ ratios were consistently lower (P < .001). The ELIFAB assay was paralleled by low sIgE/sIgG₄ ratios in VIT patients, showing markedly higher allergen-blocking capacity (P < .001). An almost complete inhibition of the basophil response was seen in all patients treated with vespid venom, but not in those treated with bee venom. Four weeks after the sting, sIgE and sIgG₄ levels were increased in allergic and asymptomatically sensitized patients, but not in VIT patients.

CONCLUSION

Immunological responses after stings varied in bee and vespid venom-allergic patients. In patients under VIT, sIgE and sIgG₄ remained completely stable after sting challenges. Monitoring VIT efficacy was only possible in vespid venom allergy, and the sIgG₄ threshold for rVes v 5 had the highest sensitivity to confirm tolerance. The BAT inhibition test was the most reliable tool to confirm tolerance on an individual basis.

Allergen-specific immunotherapy of Hymenoptera venom allergy - also a matter of diagnosis

Stings of hymenoptera can induce IgE-mediated hypersensitivity reactions in venom-allergic patients, ranging from local up to severe systemic reactions and even fatal anaphylaxis. Allergic patients' quality of life can be mainly improved by altering their immune response to tolerate the venoms by injecting increasing venom doses over years. This venom-specific immunotherapy is highly effective and well tolerated. However, component-resolved information about the venoms has increased in the last years. This knowledge is not only able to improve diagnostics as basis for an accurate therapy, but was additionally used to create tools which enable the analysis of therapeutic venom extracts on a molecular level. Therefore, during the last decade the detailed knowledge of the allergen composition of hymenoptera venoms has substantially improved diagnosis and therapy of venom allergy. This review focuses on state of the art diagnostic and therapeutic options as well as on novel directions trying to improve therapy.

Debates in Allergy Medicine: Allergy skin testing cannot be replaced by molecular diagnosis in the near future

Percutaneous skin prick tests (SPT) have been considered the preferred method for confirming IgE-mediated sensitization. This reliable and minimally invasive technique correlates with in vivo challenges, has good reproducibility, is easily quantified, and allows analyzing multiple allergens simultaneously. Potent extracts and a proficient tester improve its accuracy.

Molecular-based allergy diagnostics (MA-Dx) quantifies allergenic components obtained either from purification of natural sources or recombinant technology to identify the patient’s reactivity to those specific allergenic protein components. For a correct allergy diagnosis, the patient selection is crucial. MA-Dx has been shown to have a high specificity, however, as MA-Dx testing can be ordered by any physician, the pre-selection of patients might not always be optimal, reducing test specificity. Also, MA-Dx is less sensitive than in vitro testing with the whole allergen or SPT. Secondly, no allergen-specific immunotherapy (AIT) trial has yet shown efficacy with patients selected on the basis of their MA-Dx results. Thirdly, why would we need molecular diagnosis, as no molecular treatment can yet be offered? Then there are the practical arguments of costs (SPT highly cost-efficient), test availability for MA-Dx still lacking in wide areas of the world and scarce in others. As such, it is hard physicians can build confidence in the test and their interpretation of the MA-Dx results. In conclusion: as of now these techniques should be reserved for situations of complex allergies and polysensitization; in the future MA-Dx might help to reduce the number of allergens for AIT, but trials are needed to prove this concept.

Risk factors in Hymenoptera venom allergy

Abstract. Risk factors should be part of the decision, of which patient should be offered venom immunotherapy (VIT) and how VIT should be performed. Risk factors for a severe systemic anaphylactic reaction (SAR) after a Hymenoptera field sting include a preceding less severe sting reaction, a wasp sting, an increased baseline serum tryptase concentration (BSTC), mastocytosis, older age, ACE inhibitor medication, and male gender. During VIT, treatment with honey bee venom is the most important risk factor for a SAR. Further risk factors include a high BSTC (for vespid VIT only), presence of venom specific IgE in serum, any antihypertensive medication during therapy, and an ultra-rush protocol for build-up. Treatment failure is more common in patients suffering from honey bee venom allergy, high BSTC (for vespid VIT only) or mastocytosis, and in those who had experienced side effects during VIT. Besides discontinuing antihypertensive medication or switching to a moderate type of dose increase during build-up, little can be done to minimize the risks associated with VIT. Increasing the maintenance dose may improve the efficacy of VIT. In patients with a particularly high risk for treatment failure, or in case of treatment failure, VIT should include an increased maintenance dose right from the beginning. Usually, 200 µg will be sufficient.

[Insect venom allergies : Update 2016 for otorhinolaryngologists]

Due to the increasing incidence of hymenoptera venom allergies and the potentially life-threatening reactions, it is important for otolaryngologists working in allergology to have an understanding of modern diagnostic and treatment standards for this allergic disease. Molecular diagnosis with recombinant single allergens from bee and wasp venom components improves the diagnostics of insect venom allergies, particularly in patients with double-positive extract-based test results. Detection of specific sensitizations to bee or wasp venom enables double sensitizations to be better distinguished from cross-reactivity. Based on patient history and test results, the patient is initially advised on avoidance strategies and prescribed an emergency medication kit. Then, the indication for allergen-specific immunotherapy (AIT) is evaluated. The dose-increase phase can be performed using conventional, cluster, rush, or ultra-rush schedules, whereby rapid desensitization (rush AIT) performed in the clinic seems to be particularly effective as initial treatment.

Risk and safety requirements for diagnostic and therapeutic procedures in allergology: World Allergy Organization Statement

One of the major concerns in the practice of allergy is related to the safety of procedures for the diagnosis and treatment of allergic disease. Management (diagnosis and treatment) of hypersensitivity disorders involves often intentional exposure to potentially allergenic substances (during skin testing), deliberate induction in the office of allergic symptoms to offending compounds (provocation tests) or intentional application of potentially dangerous substances (allergy vaccine) to sensitized patients. These situations may be associated with a significant risk of unwanted, excessive or even dangerous reactions, which in many instances cannot be completely avoided. However, adverse reactions can be minimized or even avoided if a physician is fully aware of potential risk and is prepared to appropriately handle the situation. Information on the risk of diagnostic and therapeutic procedures in allergic diseases has been accumulated in the medical literature for decades; however, except for allergen specific immunotherapy, it has never been presented in a systematic fashion. Up to now no single document addressed the risk of the most commonly used medical procedures in the allergy office nor attempted to present general requirements necessary to assure the safety of these procedures. Following review of available literature a group of allergy experts within the World Allergy Organization (WAO), representing various continents and areas of allergy expertise, presents this report on risk associated with diagnostic and therapeutic procedures in allergology and proposes a consensus on safety requirements for performing procedures in allergy offices. Optimal safety measures including appropriate location, type and required time of supervision, availability of safety equipment, access to specialized emergency services, etc. for various procedures have been recommended. This document should be useful for allergists with already established practices and experience as well as to other specialists taking care of patients with allergies.

Short-, Intermediate-, and Long-Term Changes in Basophil Reactivity Induced by Venom Immunotherapy

PURPOSE

The basophil activation test (BAT) has been used to monitor venom immunotherapy (VIT) due to its high specificity. A previous study has reported a good correlation between a significant decrease in basophil activation during 5 years of VIT and clinical protection assessed by sting challenge. The following prospective study was performed to examine changes in basophil reactivity over a complete VIT period of 5 years.

METHODS

BAT in a dose-response curve was studied prospectively in 10 hymenoptera venom-allergic patients over 5 years of VIT. BAT was performed at the time of diagnosis, 1 month after finishing the VIT build-up phase, and 3, 6, 12, 24, and 60 months after beginning treatment. The repeated measures ANOVA was applied to evaluate basophil activation changes throughout VIT. A cross-sectional study was also performed in 6 patients who received treatment for more than 3 years, and in another 12 patients who followed immunotherapy for at least 5 years.

RESULTS

An early activation decrease was observed during the first 3 months of treatment, compared to pre-treatment values. This activation decrease was not maintained 6 to 18 months after treatment, but was observed again after 2 years of treatment, and maintained until the completion of the 5-year immunotherapy period. In cross-sectional analysis, the 6 patients who received treatment for 3 years, and 9 of the 12 patients who received treatment for 5 years, had negative BAT results. Three patients in this last group had positive BAT results and 2 patients had systemic reactions after field stings.

CONCLUSIONS

BAT appears to be an optimal non-invasive test for close monitoring of VIT.

Comparing the ability of molecular diagnosis and CAP-inhibition in identifying the really causative venom in patients with positive tests to Vespula and Polistes species

Background

Cross-reactivity among Hymenoptera venoms is an important issue when prescribing venom immunotherapy (VIT). Using all venoms eliciting a positive response results in treatment excess and unjustified cost increase. The first in vitro method that helped to identify the really causative venom was RAST-inhibition, but in latest years also molecular allergy (MA) diagnostics, that detects specific sIgE to single venom allergens, was introduced. We compared the two methods in patients with double sensitization to Vespula spp. and Polistes spp.

Methods

Fifty-four patients with anaphylactic reactions to Hymenoptera stings and positive results to skin tests and sIgE measurement with whole venom from Vespula spp. and Polistes dominula were included in the study. Sera from all patients were analyzed by CAP-inhibition (Thermo Fisher Scientific, Uppsala, Sweden) and MA diagnostics with recombinant Ves v 1, Ves v 5 and Pol d 5.

Results

By the data obtained from MA technique, VIT would have been prescribed to 7 patients for Polistes, to 6 for Vespula, and to 41 for both venoms. With the data from CAP inhibition, it would have been a prescription to 15 patients for Polistes, to 28 for Vespula, and to 11 for both venoms. A good concordance between the results of MA and CAP-inhibition was found only when the value in kU/l of Ves v 5 were about twice those of Pol d 5, and vice versa.

Conclusions

These findings suggest that in the choice of the venom to be used for VIT CAP-inhibition remains a pivotal tool, because the significance of in vitro inhibition is definite and provides a diagnostic importance higher than MA in patients with positive tests to both Vespula and Polistes spp.

Determinants of venom-specific IgE antibody concentration during long-term wasp venom immunotherapy

Background

Venom immunotherapy (VIT) is an effective treatment for subjects with systemic allergic reactions (SR) to Hymenoptera stings, however there are few studies concerning the relevance of the venom specific IgE changes to decide about VIT cessation. We assessed IgE changes during a 5-year VIT, in patients stung and protected within the first 3 years (SP 0–3) or in the last 2 years (SP 3–5), and in patients not stung (NoS), to evaluate possible correlations between IgE changes and clinical protection.

Methods

Yellow jacket venom (YJV)-allergic patients who completed 5 years of VIT were retrospectively evaluated. Baseline IgE levels and after the 3rd and the 5th year of VIT were determined; all patients were asked about field stings and SRs.

Results

A total of 232 YJV-allergic patients were included and divided into the following groups: 84 NoS, 72 SP 0–3 and 76 SP 3–5. IgE levels decreased during VIT compared to baseline values (χ² = 346.029, p < 0.001). Recent vespid stings accounted for significantly higher IgE levels despite clinical protection. IgE levels after 5 years of VIT correlated significantly with Mueller grade (F = 2.778, p = 0.012) and age (F = 6.672, p = 0.002). During follow-up from 1 to 10 years after VIT discontinuation, 35.2 % of the contacted patients reported at least one field sting without SR.

Conclusions

The yellow jacket-VIT temporal stopping criterion of 5 years duration did not result in undetectable IgE levels, despite a long-lasting protection. A mean IgE decrease from 58 to 70 % was observed, and it was less marked in elderly patients or in subjects with higher Mueller grade SR.

Anaphylaxis to insect venom allergens: role of molecular diagnostics

Anaphylaxis due to Hymenoptera stings is one of the most severe consequences of IgE-mediated hypersensitivity reactions. Although allergic reactions to Hymenoptera stings are often considered as a general model for the underlying principles of allergic disease, diagnostic tests are still hampered by a lack of specificity and venom immunotherapy by severe side effects and incomplete protection. In recent years, the knowledge about the molecular composition of Hymenoptera venoms has significantly increased and more and more recombinant venom allergens with advanced characteristics have become available for diagnostic measurement of specific IgE in venom-allergic patients. These recombinant venom allergens offer several promising possibilities for an improved diagnostic algorithm. Reviewed here are the current status, recent developments, and future perspectives of molecular diagnostics of venom allergy. Already to date, it is foreseeable that component-resolution already has now or will in the future have the potential to discriminate between clinically significant and irrelevant sensitization, to increase the specificity and sensitivity of diagnostics, to monitor immunotherapeutic intervention, and to contribute to the understanding of the immunological mechanisms elicited by insect venoms.

Stinging insect allergy: current perspectives on venom immunotherapy

Systemic allergic reactions to insect stings affect up to 5% of the population during their lifetime, and up to 32% of beekeepers. Such reactions can be fatal, albeit very rarely, and fear of a further systemic reaction (SR) can lead to significant anxiety and quality of life impairment. A recent Cochrane systematic review confirmed that venom immunotherapy (VIT) is an effective treatment for people who have had a systemic allergic reaction to an insect sting. VIT reduces risk of a further SR (relative risk 0.10, 95% confidence interval 0.03-0.28), but VIT also reduces risk of a future large local reaction, and significantly improves disease-specific quality of life. However, health economic analysis showed that VIT is generally not cost effective for preventing future SRs; most people are stung infrequently, most SRs resolve without long-term consequences, and a fatal outcome is extremely rare. VIT only becomes cost effective if one is stung frequently (eg, beekeepers) or if quality of life improvement is considered. Thus, for most people with insect sting allergy, anxiety and quality of life impairment should be the overriding consideration when making treatment decisions, highlighting the importance of a patient-centered approach. Areas which need to be explored in future research include efforts to improve the safety and convenience of VIT such as the use of sublingual immunotherapy; quality of life effects of venom allergy in children and adolescents as well as their parents; and the optimal duration of treatment.

Venom immunotherapy: an updated review

Venom immunotherapy (VIT) is the most effective form of specific immunotherapy to date. Hitherto, several relevant queries remain unanswered, namely optimal doses, duration, and means of assessment. Important progress has been lately made in terms of diagnosis by means of component-resolved diagnosis. Moreover, basophil activation test results in patients with negative serum immunoglobulin E (IgE) and skin prick test confer this technique a promising future, although these outcomes shall be considered with caution. This review aims to unravel the important advances made on diagnosis, management, and prognosis and also focuses on several undetermined aspects of VIT.

Clinical effectiveness of hymenoptera venom immunotherapy: a prospective observational multicenter study of the European academy of allergology and clinical immunology interest group on insect venom hypersensitivity

BACKGROUND

Treatment failure during venom immunotherapy (VIT) may be 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 with the frequency of VIT failure during the maintenance phase.

METHODS

In this observational prospective multicenter study, we followed 357 patients with established honey bee or vespid venom allergy after the maintenance dose of VIT had been reached. In all patients, VIT effectiveness was either verified by sting challenge (n = 154) or patient self-reporting of the outcome of a field sting (n = 203). Data were collected on BTC, age, gender, preventive use of anti-allergic drugs (oral antihistamines and/or corticosteroids) right after a field sting, venom dose, antihypertensive medication, type of venom, side effects during VIT, severity of index sting reaction preceding VIT, and duration of VIT. Relative rates were calculated with generalized additive models.

RESULTS

22 patients (6.2%) developed generalized symptoms during sting challenge or after a field sting. A strong association between the frequency of VIT failure and BTC could be excluded. Due to wide confidence bands, however, weaker effects (odds ratios <3) of BTC were still possible, and were also suggested by a selective analysis of patients who had a sting challenge. The most important factor associated with VIT failure was a honey bee venom allergy. Preventive use of anti-allergic drugs may be associated with a higher protection rate.

INTERPRETATION

It is unlikely that an elevated BTC has a strong negative effect on the rate of treatment failures. The magnitude of the latter, however, may depend on the method of effectiveness assessment. Failure rate is higher in patients suffering from bee venom allergy.

Vitellogenins are new high molecular weight components and allergens (Api m 12 and Ves v 6) of Apis mellifera and Vespula vulgaris venom

BACKGROUND/OBJECTIVES

Anaphylaxis due to hymenoptera stings is one of the most severe clinical outcomes of IgE-mediated hypersensitivity reactions. Although allergic reactions to hymenoptera stings are often considered as a general model for the underlying principles of allergic disease, venom immunotherapy is still hampered by severe systemic side effects and incomplete protection. The identification and detailed characterization of all allergens of hymenoptera venoms might result in an improvement in this field and promote the detailed understanding of the allergological mechanism. Our aim was the identification and detailed immunochemical and allergological characterization of the low abundant IgE-reactive 200 kDa proteins of Apis mellifera and Vespula vulgaris venom.

METHODS/PRINCIPAL FINDINGS

Tandem mass spectrometry-based sequencing of a 200 kDa venom protein yielded peptides that could be assigned to honeybee vitellogenin. The coding regions of the honeybee protein as well as of the homologue from yellow jacket venom were cloned from venom gland cDNA. The newly identified 200 kDa proteins share a sequence identity on protein level of 40% and belong to the family of vitellogenins, present in all oviparous animals, and are the first vitellogenins identified as components of venom. Both vitellogenins could be recombinantly produced as soluble proteins in insect cells and assessed for their specific IgE reactivity. The particular vitellogenins were recognized by approximately 40% of sera of venom-allergic patients even in the absence of cross-reactive carbohydrate determinants.

CONCLUSION

With the vitellogenins of Apis mellifera and Vespula vulgaris venom a new homologous pair of venom allergens was identified and becomes available for future applications. Due to their allergenic properties the honeybee and the yellow jacket venom vitellogenin were designated as allergens Api m 12 and Ves v 6, respectively.

Basophil response and the induction of a tolerance in venom immunotherapy: a long-term sting challenge study

BACKGROUND

There is no in vitro test to predict the induction of long-term tolerance in patients treated with venom immunotherapy (VIT). The aim of this study was to investigate whether immunotherapy-induced changes in basophil responsiveness reflect a state of protection and the induction of a tolerance.

METHODS

Twenty-three patients with allergic reaction after Hymenoptera sting (11 wasp and 12 honeybee) were treated with VIT. In all patients, a CD63 basophil activation test was performed before the beginning of immunotherapy, after 1 year and after completing 4-6.5 years of immunotherapy (approximately 1 year after stopping). The tolerance was then evaluated by a sting challenge test. The basophil activation test was repeated 3-6 months after the challenge.

RESULTS

Twenty-two subjects showed a negative sting challenge, and one subject, a positive sting challenge. Allergen-specific basophil response remained unchanged after 1 year of immunotherapy. However, after immunotherapy, a significant and approximately fourfold decrease was demonstrated in all tolerant subjects mainly in response to submaximal 0.1 μg/ml allergen concentration. This depression was sustained and did not change with the sting challenge test. In a nontolerant patient with a positive sting challenge, basophil response did not change.

CONCLUSIONS

Our results suggest that the depression of allergen-specific basophil response seems to be associated with the induction of a tolerance after completing a course of VIT.

Insect stings: clinical features and management

BACKGROUND

In human beings, local and systemic reactions can be caused both by blood-sucking insects and by venomous insect stings. In Central Europe, the insects that most commonly cause such reactions are honeybees, certain social wasps, mosquitoes, and flies.

METHODS

This article is based on a selective literature review, including guidelines from Germany and abroad.

RESULTS

Insect venom induces a toxic reaction at the site of the sting. Large local reactions are due to allergy and occur in up to 25% of the population; as many as 3.5% develop IgE-mediated, potentially life-threatening anaphylaxis, of which about 20 people die in Germany each year. Mastocytosis is found in 3% to 5% of patients with sting anaphylaxis, rendering these patients prone to very severe reactions. Blood-sucking by hematophagous insects can elicit a local allergic reaction, presenting as a wheal or papule, in at least 75% of the population. Large local reactions may ensue, but other diseases are rare. The acute symptoms of an insect sting are treated symptomatically. Patients who have had a systemic reaction or a large local reaction due to insect allergy must take permanent measures to avoid further allergen contact, and to make sure they can treat themselves adequately if stung again. Most patients with systemic anaphylactic reactions to bee or wasp stings need specific immunotherapy.

CONCLUSION

Insect stings can cause severe disease. Anaphylaxis due to bee or wasp stings is not a rare event; specific immunotherapy protects susceptible persons from further, potentially life-threatening reactions.

Api m 10, a genuine A. mellifera venom allergen, is clinically relevant but underrepresented in therapeutic extracts

BACKGROUND

Generalized systemic reactions to stinging hymenoptera venom constitute a potentially fatal condition in venom-allergic individuals. Hence, the identification and characterization of all allergens is imperative for improvement of diagnosis and design of effective immunotherapeutic approaches. Our aim was the immunochemical characterization of the carbohydrate-rich protein Api m 10, an Apis mellifera venom component and putative allergen, with focus on the relevance of glycosylation. Furthermore, the presence of Api m 10 in honeybee venom (HBV) and licensed venom immunotherapy preparations was addressed.

METHODS

Api m 10 was produced as soluble, aglycosylated protein in Escherichia coli and as differentially glycosylated protein providing a varying degree of fucosylation in insect cells. IgE reactivity and basophil activation of allergic patients were analyzed. For detection of Api m 10 in different venom preparations, a monoclonal human IgE antibody was generated.

RESULTS

Both, the aglycosylated and the glycosylated variant of Api m 10 devoid of cross-reactive carbohydrate determinants (CCD), exhibited IgE reactivity with approximately 50% of HBV-sensitized patients. A corresponding reactivity could be documented for the activation of basophils. Although the detection of the native protein in crude HBV suggested content comparable to other relevant allergens, three therapeutical HBV extracts lacked detectable amounts of this component.

CONCLUSION

Api m 10 is a genuine allergen of A. mellifera venom with IgE sensitizing potential in a significant fraction of allergic patients independent of CCD reactivity. Thus, Api m 10 could become a key element for component-resolved diagnostic tests and improved immunotherapeutic approaches in hymenoptera venom allergy.

Congruence of the current practices in Hymenoptera venom allergic patients in Poland with EAACI guidelines

INTRODUCTION

Venom immunotherapy (VIT) practice is the definitive treatment for patients with potentially fatal allergic reactions to Hymenoptera stings. The aim is assesing compliance of VIT practice in Poland with the current European Academy of Allergy and Clinical Immunology (EAACI) guidance.

MATERIAL AND METHODS

A multicentre study was carried out using a structured questionnaire which was sent by post to all VIT practitioners in Poland. Some questionnaire items were altered, in comparison to original version by adding additional answer options or alowing multiple answer option. The response rate was 100%. The obtained results were compared with the published EAACI guidelines.

RESULTS

Twenty-six Polish centres took part in the survey. SSIgE and skin prick tests (SPT) are together used as the first line of investigation, whereas confirmatory intradermal tests (IDT) are applied in half of centres. Only a few centres measure baseline serum tryptase levels. The ultra-rush protocol is preferred. Antihistamine pre-medication is routinely practiced. A target dose equal to 100 µg is used in most centres. A 6-week interval between booster doses is the most frequent. Five years is considered as an optimal VIT duration. Before the VIT completion, SSIgE is evaluated in fifty percent of centres, whereas sting challenge is considered by half of responders.

CONCLUSIONS

There are some differences between current practice in Poland and the EAACI recommendations, indicating areas requiring better compliance. Comparision between Poland and the United Kingdom revealed that health service organization and health care funding may play a major role in the provision of allergy services. This may affect the extent to which international guidance may be applied in individual countries. It is worth considering conducting the same survey in other European countries.

Importance of basophil activation testing in insect venom allergy

BACKGROUND

Venom immunotherapy (VIT) is the only effective treatment for prevention of serious allergic reactions to bee and wasp stings in sensitized individuals. However, there are still many questions and controversies regarding immunotherapy, like selection of the appropriate allergen, safety and long term efficacy.

METHODS

Literature review was performed to address the role of basophil activation test (BAT) in diagnosis of venom allergy.

RESULTS

In patients with positive skin tests or specific IgE to both honeybee and wasp venom, IgE inhibition test can identify sensitizing allergen only in around 15% and basophil activation test increases the identification rate to around one third of double positive patients. BAT is also diagnostic in majority of patients with systemic reactions after insect stings and no detectable IgE. High basophil sensitivity to allergen is associated with a risk of side effects during VIT. Persistence of high basophil sensitivity also predicts a treatment failure of VIT.

CONCLUSION

BAT is a useful tool for better selection of allergen for immunotherapy, for identification of patients prone to side effects and patients who might be treatment failures. However, long term studies are needed to evaluate the accuracy of the test.

Dissecting cross-reactivity in hymenoptera venom allergy by circumvention of alpha-1,3-core fucosylation

Hymenoptera venom allergy is known to cause life-threatening and sometimes fatal IgE-mediated anaphylactic reactions in allergic individuals. About 30-50% of patients with insect venom allergy have IgE antibodies that react with both honeybee and yellow jacket venom. Apart from true double sensitisation, IgE against cross-reactive carbohydrate determinants (CCD) are the most frequent cause of multiple reactivities severely hampering the diagnosis and design of therapeutic strategies by clinically irrelevant test results. In this study we addressed allergenic cross-reactivity using a recombinant approach by employing cell lines with variant capacities of alpha-1,3-core fucosylation. The venom hyaluronidases, supposed major allergens implicated in cross-reactivity phenomena, from honeybee (Api m 2) and yellow jacket (Ves v 2a and its putative isoform Ves v 2b) as well as the human alpha-2HS-glycoprotein as control, were produced in different insect cell lines. In stark contrast to production in Trichoplusia ni (HighFive) cells, alpha-1,3-core fucosylation was absent or immunologically negligible after production in Spodoptera frugiperda (Sf9) cells. Consistently, co-expression of honeybee alpha-1,3-fucosyltransferase in Sf9 cells resulted in the reconstitution of CCD reactivity. Re-evaluation of differentially fucosylated hyaluronidases by screening of individual venom-sensitised sera emphasised the allergenic relevance of Api m 2 beyond its carbohydrate epitopes. In contrast, the vespid hyaluronidases, for which a predominance of Ves v 2b could be shown, exhibited pronounced and primary carbohydrate reactivity rendering their relevance in the context of allergy questionable. These findings show that the use of recombinant molecules devoid of CCDs represents a novel strategy with major implications for diagnostic and therapeutic approaches.

[Venom immunotherapy. Side effects and efficacy of treatment]

Venom immunotherapy (VIT) protects patients with Hymenoptera venom anaphylaxis from subsequent potentially life-threatening reactions. The most important side effect are systemic anaphylactic reactions (SAR). Compared to the administration of aqueous extracts according to a rush protocol, the frequency of systemic and also local side effects will be lower if depot extracts are used and a slow conventional dose schedule is used, as compared to rush desensitization with aqueous extracts. However, protection often has to be achieved rapidly, and adequate surveillance of sufficient duration is hardly feasible in outpatients. Therefore, VIT according to rush schedules in inpatients remains indispensable. Pre-treatment with H(1)-blocking antihistamines reduces frequency and intensity of local and mild systemic adverse reactions during VIT. Up to 25% of patients again develop a SAR when re-stung while on VIT with the usual maintenance dose of 100 microg venom. Patients with honeybee venom allergy or with mastocytosis are at a higher risk for treatment failure. Almost all of them will become fully protected by increasing the maintenance dose, 200 microg venom being sufficient in most cases. Patients with significant risk factors may be treated from the beginning with an elevated maintenance dose, particularly when they are allergic to honeybee venom.

Insect sting anaphylaxis

Anaphylaxis to insect stings has occurred in 3% of adults and can be fatal even on the first reaction. Large local reactions are more frequent but rarely dangerous. The chance of a systemic reaction to a sting is low (5% to 10%) in large local reactors and in children with mild (cutaneous) systemic reactions, and varies between 25% and 70% in adults depending on the severity of previous sting reactions. Venom skin tests are most accurate for diagnosis, but the radioallergosorbent test (RAST) is an important complementary test. The degree of sensitivity on skin test or RAST does not predict the severity of a sting reaction reliably. Venom sensitization can be detected in 25% of adults, so the history is most important. Venom immunotherapy is 75% to 98% effective in preventing sting anaphylaxis. Most patients can discontinue treatment after 5 years, with very low residual risk of a severe sting reaction.

[Diagnosis and treatment of insect venom allergy. An important allergic issue for the ear, nose and throat specialist]

The increasing incidence and the potentially life-threatening reactions to venom stings indicate the necessity for otolaryngologists to have a basic knowledge of the diagnosis and treatment of venom allergy. The diagnosis of insect venom allergy is based on the history, skin prick testing (ideally performed as a titration series), and in vitro analysis of specific IgE antibodies to venoms. An emergency medication kit should be prescribed for the patient in case of future venom stings, comprising an H1-blocking antihistamine, a steroid and an adrenaline pen for self-injection. Subcutaneous allergen-specific immunotherapy (sSIT) is the standard treatment to avoid allergic reactions following venom stings in the future. SIT is indicated following all immediate-type reactions to venom stings; contraindications relate to the general recommendations of allergen-specific immunotherapy. Aqueous as well as alum-adsorbed depot allergen preparations can be used for subcutaneous injections. The important dose-increase phase can be performed using conventional, cluster, rush or ultra-rush schedules. Specific immunotherapy is successful in nearly 90% to 100% of patients after 3-5 years of treatment.

Continuous immunotherapy for hymenoptera venom allergy using six month intervals

BACKGROUND

Specific immunotherapy for hymenoptera venom allergy (venom immunotherapy [VIT]) is safe and effective. The duration of treatment is still open for discussion because there is no reliable routine test to determine the real risk of serious anaphylactic reactions. This prospective study, which spans more than 25 years, was conducted to ensure unlimited protection through continuous VIT. To reduce workload and cost, the maintenance interval was increased to 6 months without increasing the rate of adverse events. Only patients with continuous follow-up by our service were included in this study.

PATIENTS AND METHODS

VIT was conducted in 176 patients (125 allergic to wasp venom, 20 to bee venom, 31 to both) over a mean of 7.14 years (1.16-25.49). Total and specific IgE were determined on a regular basis.

RESULTS

A total of 162 re-stings were reported. Of these, 154 produced a strictly local reaction, seven produced non-serious reactions and one produced a systemic reaction similar to that produced by the initial sting before VIT. Total and specific IgE diminished during VIT. Substantial adverse effects were rare and never life-threatening. The effects occurred during observation in the ward and were controlled according to the treatment protocol recommended by a German expert consensus meeting on the treatment of anaphylactoid reactions. VIT was terminated in only one patient due to recurrent adverse effects.

CONCLUSION

Continuous VIT at 6-monthly maintenance intervals conferred permanent protection in patients allergic to bee and wasp venoms and was found to be a safe and effective alternative to current standard protocols.

[Specific immunotherapy. Hyposensitization with allergens]

Successful allergen-specific immunotherapy (SIT) induces complex immunologic chan-ges resulting in reduced allergic inflammatory reactions. SIT has long-term effects in mild forms of inhalant allergies and is effective even when standard pharmacotherapy fails. Moreover, the risk to develop additional allergic sensitizations and the development of asthma is significantly reduced in children with allergic rhinitis. SIT is the treatment of choice in patients with systemic reactions to hymenoptera venoms. Although the exact effector mechanisms of SIT still have to be clarified, the most probable effect is a modulation of regulatory T cells associated with a switch of allergen-specific B-cells towards IgG4 production. The critical point to insure efficacy and safety is the selection of patients and allergens, task best performed by a specialist trained in allergology. Further details are available in the position papers of the German allergy societies - DGAI(Deutsche Gesellschaft fiir Allergologie und Klinische Immunologie) and ADA (Arzte-verband Deutscher Allergologen) - which can be found at www.dgaki.de.

Specific immunotherapy in Albanian patients with anaphylaxis to hymenoptera venoms

BACKGROUND

Severe allergic reactions during rush-specific immunotherapy (Rush-SIT) may occur in the treatment of hymenoptera sting allergy. The objective of the present study was to examine the characteristics of allergic reactions during Rush-SIT in a cohort of patients with allergy towards hymenoptera venom in the mediterranean population of Albania.

METHODS

A retrospective study was performed using the clinical reports of 37 patients with venom of bee (apinae), wasp (vespidae, subfamily vespinae) or paperwasp (vespidae, subfamily polistinae) allergy treated with Rush-SIT between 1987 and 1996. After hymenoptera sting allergy diagnosis according to anamnesis and intracutaneous tests the patient were treated with Rush-SIT. The protocol lasted 3 - 4 d with an increase in the concentration from 0.01 microg/ml to 100 microg/ml. Anaphylactic reactions were classified according to the Mueller-classification.

RESULTS

The frequency of reactions during Rush-SIT for bee-venom was 4.7% and for wasp-venom was 1.5% (p < 0.01). The mean frequency of reactions of Mueller grade II for the bee-venom Rush-SIT patients during the first 4 d (= 26 injections) was 0.73 and for the wasp-venom Rush-SIT patients 0.15. No patient experienced a third-degree reaction. 94.6% of the patient supported an end dose of 100 microg.

CONCLUSIONS

Rush-SIT is a reliable method for the treatment of anaphylactic reactions to hymenoptera venom even in less developed countries. Bee-venom Rush-SIT was found to cause higher numbers allergic reactions than wasp or paperwasp Rush-SIT.

[Allergy to hymenoptera venoms in children]

Incidence of hymenoptera venom allergy in children is about 0.4 to 0.8%. Clinical features usually range from urticaria to anaphylaxis. Fatal reactions can occur but with less frequency than in adults. Allergologic investigations must be performed in children with systemic or generalized reactions after hymenoptera stings, which may lead to venom immunotherapy. Venom immunotherapy is well reported, but protocols differ according to the authors: ultra-rush in 3 h, accelerated in 3 to 5 days and semi-rush in 2 to 8 weeks. Results are always excellent (90 to 100%). We report our experience with 91 children receiving venom immunotherapy. Clinical history and positivity of skin tests indicated immunotherapy. Clinical symptoms were anaphylaxis (15.3%), serious reaction (37.3%) strong reaction (34%), and mild reaction (7.6%). Changes in immunological parameters revealed wide individual variations, not differing from data in the literature, with no correlation with evolution of immunotherapy. Venom immunotherapy appeared with good tolerability in children, whatever the protocol used.