Unraveling wasp sensitization in a patient with systemic mastocytosis by CAP-inhibition assay.

Systemic mastocytosis (SM) is a clonal mast cell disorder that can lead to potentially severe anaphylactic reactions. Hymenoptera sting is one of the most frequent triggers of anaphylaxis in these patients, and diagnosis of indolent SM (ISM) without skin involvement (ISMs) is not rare. In this subgroup of patients, venom immunotherapy (VIT) is an effective treatment decreasing subsequent systemic reactions, and lifelong administration is recommended. An individualized diagnosis is necessary to offer the most adequate VIT, and molecular diagnosis (MD) may be useful to discriminate between primary sensitization and cross-reactivity. Nevertheless, other techniques such as ImmunoCAP inhibition assays may be necessary to identify the genuine sensitization to offer the most suitable VIT. We present a male patient with an anaphylactic reaction following several wasp stings. The patient was diagnosed with ISM, and allergy to both Polistes dominula and Vespula sp venom was confirmed. In this scenario, MD did not discriminate between a genuine double sensitization and venom cross-reactivity between both vespids. Thus, CAP-inhibition assay was performed. This case indicated the importance of an accurate diagnosis of hymenoptera venom allergy (HVA). It also highlights the usefulness of CAP-inhibition assays when MD fails to distinguish between genuine double Polistes-Vespula sensitization and cross-reactivity.

Prevalent bee venom genes evolved before the aculeate stinger and eusociality.

BACKGROUND: Venoms, which have evolved numerous times in animals, are ideal models of convergent trait evolution. However, detailed genomic studies of toxin-encoding genes exist for only a few animal groups. The hyper-diverse hymenopteran insects are the most speciose venomous clade, but investigation of the origin of their venom genes has been largely neglected. RESULTS: Utilizing a combination of genomic and proteo-transcriptomic data, we investigated the origin of 11 toxin genes in 29 published and 3 new hymenopteran genomes and compiled an up-to-date list of prevalent bee venom proteins. Observed patterns indicate that bee venom genes predominantly originate through single gene co-option with gene duplication contributing to subsequent diversification. CONCLUSIONS: Most Hymenoptera venom genes are shared by all members of the clade and only melittin and the new venom protein family anthophilin1 appear unique to the bee lineage. Most venom proteins thus predate the mega-radiation of hymenopterans and the evolution of the aculeate stinger.

Blood Transcriptomics Identifies Multiple Gene Expression Pathways Associated with the Clinical Efficacy of Hymenoptera Venom Immunotherapy.

Allergen-specific venom immunotherapy (VIT) is a well-established therapy for Hymenoptera venom allergy (HVA). However, the precise mechanism underlying its clinical effect remains uncertain. Our study aimed to identify the molecular mechanisms associated with VIT efficiency. We prospectively included 19 patients with HVA undergoing VIT (sampled before the beginning of VIT, after reaching the maintenance dose, one year after finishing VIT, and after a sting challenge) and 9 healthy controls. RNA sequencing of whole blood was performed on an Illumina sequencing platform. Longitudinal transcriptomic profiling revealed the importance of the inhibition of the NFκB pathway and the downregulation of DUX4 transcripts for the early protection and induction of tolerance after finishing VIT. Furthermore, successful treatment was associated with inhibiting Th2, Th17, and macrophage alternative signalling pathways in synergy with the inhibition of the PPAR pathway and further silencing of the Th2 response. The immune system became activated when reaching the maintenance dose and was suppressed after finishing VIT. Finally, successful VIT restores the immune system's balance to a state similar to that of healthy individuals. Our results underline the important role of the inhibition of four pathways in the clinical effect of VIT: Th2, Th17, NFκB, and macrophage signalling. Two biomarkers specific for successful VIT, regardless of the time of sampling, were C4BPA and RPS10-NUDT3 and should be further tested as potential biomarkers.

LAD2 mast cell activation test associates with the reaction severity and diagnoses BAT nonresponders in Hymenoptera venom allergy.

BACKGROUND AND OBJECTIVE: The usefulness of the mast cell activation test (MAT) in diagnosing patients with uninterpretable basophil activation test (BAT) caused by nonresponding basophils has not yet been addressed. It should be further evaluated if the results of MAT are associated with the severity of the allergic reaction. METHODS: We recruited 39 Hymenoptera venom allergic (HVA) patients, 22 non-sensitized controls, and 37 BAT nonresponding HVA patients. Specific IgE levels for honey bee venom (HBV), yellow jacket venom (YJV) and total IgEs were quantified using the Immulite system. BAT and MAT with LAD2 cells in response to HBV and YJV were performed. RESULTS: We first optimized the susceptibility of LAD2 cells to IgE-mediated degranulation in HVA and showed that prestimulation with IL-33 and IL-6 significantly increased the LAD2 cells´ responsiveness to allergen stimulation (P<0.01). LAD2 MAT results correlated with BAT results, and patients with severe sting reactions (Mueller grades IV or III) had a median 2-fold higher LAD2 MAT than the patients with nonsevere sting reactions (Mueller grades II, I or LLR) (P<0.05). Further, LAD2 MAT provided conclusive results in 54.1% (20 of 37) of HVA patients with nonresponding basophils in the BAT. CONCLUSION: The LAD2 MAT represents a new diagnostic tool for HVA patients with nonresponding basophils. Further, LAD2 MAT can identify patients at risk of severe sting reactions and thus can help guide recommendations for venom immunotherapy and improve the management of patients with HVA.

Fatal Hymenoptera Venom-Triggered Anaphylaxis in Patients with Unrecognized Clonal Mast Cell Disorder-Is Mastocytosis to Blame?

Hymenoptera venom-triggered anaphylaxis (HVA) affects up to 8.9% of the general population and is the most frequent cause of anaphylaxis in adults, accounting for approximately 20% of all fatal anaphylaxis cases. Quite often, a fatal reaction is a victim's first manifestation of HVA. Mastocytosis represents one of the most important risk factors for severe HVA. We analyzed patients with documented fatal HVA for the presence of underlying clonal mast cell disorder (cMCD). Here, we report three cases of fatal HVA, with undiagnosed underlying cMCD identified by the presence of the peripheral blood and/or bone marrow KIT p.D816V missense variant postmortem. In the first case, anaphylaxis was the initial episode and was fatal. In the other two cases, both patients were treated with specific venom immunotherapy (VIT), nevertheless, one died of HVA after VIT discontinuation, and the other during VIT; both patients had cardiovascular comorbidities and were taking beta-blockers and/or ACE inhibitors. Our results point to the importance of screening all high-risk individuals for underlying cMCD using highly sensitive molecular methods for peripheral blood KIT p.D816V variant detection, including severe HVA and possibly beekeepers, for proper management and the need for lifelong VIT to prevent unnecessary deaths. Patients at the highest risk of fatal HVA, with concomitant cardiovascular and cMCD comorbidities, might not be protected from field stings even during regular VIT. Therefore, two adrenaline autoinjectors and lifelong VIT, and possibly cotreatment with omalizumab, should be considered for high-risk patients to prevent fatal HVA episodes.

Endothelial dysfunction of the cornea after exposure to sprayed venom from hornets.

PURPOSE: Ocular injuries due to Hymenoptera venom are uncommon and most injuries occur on the ocular surface. We reported two rare cases of corneal endothelial damage caused by hornet venom that was sprayed, not injected, through stinging in the eye. OBSERVATIONS: Case 1: A 57-year-old male patient was injured when a hornet sprayed venom into his left eye. He was referred to our hospital because the edoema and epithelial erosion of the cornea persisted. The patient presented with bullous keratopathy, asymmetrical iris atrophy, irreversible mydriasis, and glaucoma. His cataract progressed, and his best-corrected visual acuity was 0.03. Cataract surgery was performed after anti-inflammatory treatment with steroids, and Descemet-stripping automated endothelial keratoplasty was performed 6 months later. The patient recovered well postoperatively: his best-corrected visual acuity improved to 1.0 and he continued his glaucoma treatment. Case 2: A 75-year-old male patient had damage to his corneal epithelium, severe conjunctivitis, and conjunctival edoema when sprayed hornet venom entered his left eye. At initial presentation, the corneal endothelial cell density had decreased to 1042 cells/mm2. The conjunctival sac was washed, and steroid and topical antibacterial instillations were administered. His best-corrected visual acuity improved from 0.07 at the initial visit to 0.5. However, the corneal opacification and glaucoma persisted, and 3 months later the corneal endothelial cell density decreased to 846 cells/mm2. CONCLUSIONS AND IMPORTANCE: Corneal injuries caused by sprayed hornet venom are rare; however, they can cause intense anterior chamber inflammation and severe, irreversible corneal endothelial damage. In such cases, prompt initial treatment, the administration of adequate anti-inflammatory medication, and careful evaluation of the corneal endothelium are required.

Stinging insect identification in children with Hymenoptera venom allergy and their parents.

Introduction: The treatment of Hymenoptera venom allergy (HVA) is based among others on the proper identification of the culprit insect. Aim: To assess the accuracy in identifying stinging insects by children with HVA and their parents. Material and methods: Participants were recruited from a paediatric medical centre. The data on their demographics, sting history and ability of insect identification (based on pictures) were obtained using a questionnaire. The study sample consisted of 102 children with HVA and their parents as well as 98 children without HVA and their parents. Results: The rates of subjects correctly identifying insects in the groups were 91.2%, 92.5%, 78.8%, 82.4%, respectively. When compared to children with HVA, those without HVA were less likely to correctly identify the bee, bumblebee and hoverfly. In this group, the correct identification of the wasp was more common among children living in the countryside. The correct identification of the bee and bumblebee by children without HVA was more common among children living in the city. Conclusions: Some children with HVA and their parents cannot correctly identify stinging insects despite previous life-threatening allergic reactions. The ability to identify stinging insects may depend on the HVA diagnosis and place of residence.

The Lights and the Shadows of Controlled Sting Challenge With Hymenoptera.

Hymenoptera venom immunotherapy (VIT) is effective for protecting individuals with systemic allergic reactions caused by Hymenoptera stings. The need for a tool that shows the degree of protection afforded by VIT and the lack of useful biomarkers have made the sting challenge test (SCT) the gold standard for this disorder, although its use has both lights and shadows. SCT with Hymenoptera involves causing a real sting in a patient diagnosed with allergy to the venom of the stinging insect and who is undergoing treatment with specific immunotherapy. In Spain, SCT is included in the list of services offered by some hospitals and forms part of their daily clinical practice. This review aims to analyze the strengths and weaknesses of this test and to describe the standardized procedure and necessary resources, based on the experience of a group of Spanish experts and a review of the literature.

Basal Tryptase High Levels Associated with a History of Arterial Hypertension and Hypercholesterolemia Represent Risk Factors for Severe Anaphylaxis in Hymenoptera Venom-Allergic Subjects over 50 Years Old.

INTRODUCTION: Allergy to Hymenoptera venom (HV) may lead to life-threatening anaphylaxis. Some of the factors influencing the symptom's severity are still undetermined. The aim of this study was to identify the clinical aspects associated with the most severe reactions in a population with HV allergy, by comparing clinical and immunochemical biomarkers between patients with previous local large reactions (LLRs) and systemic reactions (SRs). METHODS: We selected adult patients with a history of HV allergy, with positive diagnostic tests and a correlation with one single Hymenoptera species. Age, gender, atopy, serum basal tryptase (sBT) value, total IgE, venom-specific IgE, history of hypertension, cardiovascular diseases, and hypercholesterolemia were compared between patients with previous LLRs and SRs. RESULTS: 460 adult patients (381 SRs, 79 LLRs) were included. Age (p = 0.0097), male gender (p < 0.0001), arterial hypertension (p = 0.046), hypercholesterolemia (p = 0.009), and higher sBT levels (p = 0.0004) were significantly associated with severe reactions as independent variables. Moreover, considering the previous variables as risk factors, there was a significant and progressive increase in the odds of being Mueller III + IV as the number of positive variables increased. Patients with sBT ≥6.4 ng/mL adjusted for any of the positive variables had increased the risk of Mueller grade IV reaction (p < 0.0001). CONCLUSION: According to our results, older age, male gender, arterial hypertension, hypercholesterolemia, and increased levels of sBT ≥6.4 ng/mL are risk factors for severe anaphylaxis to HV in adults. Atopy and allergic asthma do not increase the risk of HV-induced SRs.

Update on Insect Sting Anaphylaxis.

PURPOSE OF REVIEW: This review describes improvement in diagnostic accuracy, prediction of outcomes, identifying high-risk factors, and refinements of treatment that continue to evolve over the past 5-10 years. RECENT FINDINGS: The risk of anaphylaxis is relatively low (< 5%) in patients with previous large local reactions or strictly cutaneous systemic reactions, but much higher in those with moderate-to-severe anaphylaxis (40%-70%) or mastocytosis (> 90%). Use of recombinant venom allergens and basophil activation tests may improve diagnostic accuracy. Elevated serum tryptase (and possible mastocytosis) occurs in 10% of patients with insect sting allergy, and in 25% of those with hypotensive reactions. Rush VIT is proven safe and rapidly effective. There are known high-risk factors that justify treatment beyond 5 years. Diagnostic accuracy and prediction of risk have improved in recent years. There are still knowledge gaps related to prediction and management of risk with current diagnostic and therapeutic modalities.

[Allergen immunotherapy: FAQs and facts]. / Allergen-Immuntherapie: Facts und FAQs.

Allergen immunotherapy (AIT) is-when allergen avoidance is not sufficient-the only causative therapy of IgE-mediated allergies against aeroallergenes and Hymenoptera venoms. Allergens can be administered by either subcutaneous injection (SCIT) or sublingual application (SLIT); furthermore, oral immunotherapy in food allergy was also recently approved. Besides correct indication (positive history and diagnostics of IgE-mediated allergy, insufficient allergen avoidance) particular attention has to be payed to potential contraindications and risks. Furthermore, unwanted side effects, which may be life-threatening, can occur. In the following, frequently asked questions (FAQs) and facts in regard to the decision-making process for the implementation as well as the risk management of AIT are discussed.

Prevalence and characteristics of Hymenoptera venom allergy in urban school children aged 6 to 18 years living in Trabzon

Background/aim: Hymenoptera venom allergy is one of the leading causes of systemic allergic reactions in both adults and children. The present study was conducted to evaluate the prevalence and characteristics of Hymenoptera venom allergy in urban school children aged 6 to 18 years living in Trabzon. Materials and methods: In this cross-sectional, two-level survey study, children were recruited using random sampling of public primary and secondary schools. Firstly, parents were asked about their child's age and sex and whether their child had ever been stung by any kind of bee. When they responded "yes" to the last question, they attended a face-to-face interview at the outpatient clinic for the second part of the survey, which included information about history of insect stings and the presence of atopic diseases. Results: Of 17,000 children, 7904 (46.5%; 3718 males, 47.0%) returned the first-level questionnaire. A total of 4312 (54.5%) were stung at least once in their lifetime. Males had a significantly higher risk of being stung (59.4%, odds ratio: 1.44, 95% confidence interval: 1.32­1.58, p < 0.0001). The second-level questionnaire was completed for 545 (12.6%) of the children. Of 950 stings reported in 545 children, 5.2% were large local reactions (LLRs), 1.9% were generalized cutaneous reactions (GCRs), and 1.3% were systemic reactions (SRs). The stinging insect was Apis mellifera and Vespula in 66.2% and 33.8% of stings, respectively (p < 0.001). Conclusion: Hymenoptera stings are common in urban school children living in Trabzon. The most common type of allergic reaction is LLR and the most reported stinging insect is Apis mellifera.

Allergic diseases in the elderly population: a single-center experience.

BACKGROUND: Although allergic diseases are generally considered to be diseases of childhood and youth, the first symptoms of allergic diseases can be seen in old age sometimes. The aim of this study was to determine the prevalence and characteristics of allergic diseases in the elderly population admitted to the allergy unit on an outpatient basis. METHODS: The files of the patients who applied to our clinic's allergy unit during the 8-year period were retrospectively analyzed. The data of patients aged ≥ 65 years were obtained from the files of our allergy unit archive. RESULTS: A total of 1272 patients aged ≥ 65 years old were included in the study. The mean age was 70 years (range: 65-97 years). Most of the patients were female (n = 704, 55.3%). Of the patients, 887 (69.8%) presented with cutaneous symptoms, and urticaria was identified in 500 of them (56.3%). Drug hypersensitivity reactions were detected in 175 (13.7%) patients. A total of 71 (5.6%) patients had asthma, 65 (5.1%) had anaphylaxis, 48 (3.8%) had allergic rhinitis, 24 (1.9%) had hymenoptera venom allergy, and 18 (1.4%) had food allergies. Atopy history (OR = 2.323, 95% CI = 1.590-3.393, p < 0.001) and comorbidity (OR = 1.631, 95% CI = 1.050-2.533, p = 0.029) were found to be risk factors for drug hypersensitivity reactions. Male sex (OR = 3.462, 95% CI = 1.097-10.933, p = 0.034) and atopy history (OR = 14.877, 95% CI = 6.081-36.393, p < 0.001) were found to be risk factors for hymenoptera venom allergy. DISCUSSION: Diagnosis becomes difficult due to the perception that allergic diseases mainly affect young people. Clinical symptoms are not evident in the elderly and age-related difficulties are encountered in diagnostic tests. There is a need to develop specific guidelines for the diagnosis of allergic diseases in the elderly.

Venom immunotherapy in patients with clonal mast cell disorders: IgG4 correlates with protection.

BACKGROUND: Patients with clonal mast cell disorders (cMCD), systemic mastocytosis (SM) and monoclonal mast cell activation syndrome (MMAS), represent an increased risk for Hymenoptera venom anaphylaxis (HVA). Lifelong venom immunotherapy (VIT) is recommended; however, its efficacy and safety are controversial. Hence, we sought to evaluate the efficacy and safety of VIT in HVA patients with cMCD. METHODS: A retrospective study was conducted among 46 patients with Vespula venom allergy who had experienced severe HVA, 32 cMCD (22 with SM and 10 with MMAS) and 14 controls. There were no differences between cMCD patients and controls in age (58 vs 66) and duration of VIT (47 vs 48 months), respectively. RESULTS: During VIT, 11 (34%) cMCD patients experienced adverse reactions (ARs) (7% in controls), including 1 anaphylaxis. There were 23 re-stings in 17 (53%) patients during VIT. Of episodes, four (17%) presented with anaphylaxis, 14 (60%) presented with local reaction, and five (23%) were asymptomatic. In 11 episodes (48%), the patient did not take epinephrine, of these 8 (73%) presented with local reaction, and 3 (27%) were asymptomatic. Patient-based protection from anaphylaxis was 76% (4/17) in cMCD vs. 100% in controls during VIT. The venom-specific IgG4 concentrations increased during VIT (P < .001) although tryptase and IgE were unaltered. CONCLUSION: Both safety and efficacy of VIT in cMCD patients were slightly reduced than controls. Severe ARs were rare. The elevated IgG4 levels may be a biomarker for efficacy of VIT in cMCD patients, as it correlates with protection from re-stings.

Comparison of the Safety Profiles of 3 Different Hymenoptera Venom Immunotherapy Protocols: A Retrospective 2-Center Study of 143 Patients.

INTRODUCTION: Venom immunotherapy (VIT) is highly effective and the treatment of choice for patients with a history of systemic anaphylactic reactions to a Hymenoptera sting. It has been assumed that VIT protocols with a rapid dose increase during the induction phase are associated with a higher frequency of systemic reactions (SR); however, study data addressing this issue are conflicting. OBJECTIVE: The aim of this study was to compare the safety of 3 different Hymenoptera VIT protocols (half-day ultra-rush, 3-day rush, 3-week cluster). METHODS: This retrospective 2-center study included 143 Hymenoptera venom-allergic patients, who underwent 147 VIT procedures during the years 2015-2018. Twenty cluster, 75 rush, and 52 ultra-rush VIT protocols were performed with honeybee (54 protocols) and wasp (93 protocols) venom. All documented side effects were classified into large local and SR (Ring and Messmer classification). RESULTS: SR were observed during 11 (7.5%) VIT procedures and did not exceed severity grade II. SR occurred more frequently in cluster compared to accelerated protocols. This result was observed for both honeybee (cluster: 25%, rush: 8.7%, and ultra-rush: 15.8%) and wasp VIT (cluster: 12.5%, rush: 0%, and ultra-rush: 6.1%), though the differences were statistically significant only in the wasp VIT subgroup. Honeybee venom elicited more SR than wasp venom (14.8 and 3.2%, respectively, p = 0.01). The risk for SR did not depend on age, sex, concomitant antihypertensive medication, hypertryptasemia, or severity of the index sting reaction. CONCLUSION: Accelerated VIT protocols, namely, rush and ultra-rush protocols are safe therapeutic options for Hymenoptera venom-allergic patients and displayed fewer SR than cluster VIT protocols in our study.

Antigen 5 Allergens of Hymenoptera Venoms and Their Role in Diagnosis and Therapy of Venom Allergy.

PURPOSE OF REVIEW: Stings of Hymenoptera of the superfamily Vespoidea such as yellow jackets, paper wasps or stinging ants are common triggers for severe and even fatal allergic reactions. Antigen 5 allergens are potent allergens in the majority of these venoms with major importance for diagnosis and therapy. Reviewed here are the characteristics of antigen 5 allergens, their role in component-resolved diagnostics as well as current limitations of the available diagnostics for proper therapeutic decisions. RECENT FINDINGS: Antigens 5 are proteins of unknown function in Hymenoptera venoms with high allergenic potency. They represent key elements in component-resolved diagnosis to discriminate between honeybee and vespid venom allergy. However, due to their pronounced cross-reactivity, there are remaining diagnostic and therapeutic challenges that have to be addressed. Antigens 5 are highly relevant venom allergens of the Vespoidea superfamily. Although their use in component-resolved diagnosis facilitates dissection of cross-reactivity and primary allergy in double sensitization to honeybee and vespid venom, new diagnostic concepts are needed to discriminate between allergies to different vespid species.

Hymenoptera venom allergy among children in Italy: time for pediatricians to take action.

Hymenoptera venom allergy (HVA) is one of the most frequent causes of anaphylaxis following a bee, vespid or ant sting. Real-life data regarding the management of HVA in children are lacking. To address this unmet need, we carried out a survey defining the current management of HVA in children among pediatric allergists in Italy. Educational investments on the improvement of the management of pediatric patients with HVA are urgently needed, and our analysis represents a relevant instrument in targeting a roadmap with this aim. The time for pediatric allergists to take action has come, and a task force from the Rare Allergic Diseases Commission of the Italian Society of Pediatric Allergy and Immunology is working on the topic to improve pediatricians' knowledge and optimize the care of these patients.

Medical Algorithms: Diagnosis and treatment of Hymenoptera venom allergy.

Diagnosis of Hymenoptera venom allergy (HVA) is straightforward in the majority of patients, but can be challenging in double positive and test negative patients. Test results sometimes can be confusing as patients with high skin test reactivity and high specific IgE (sIgE) levels are not at risk for severe systemic sting reactions (SSR), and conversely, patients with weakly positive or even negative tests can experience severe SSR. Venom immunotherapy (VIT) is safe, highly effective, and recommended in patients with moderate to severe SSR and in patients with SSR confined to generalized skin symptoms if quality of life is impaired.