Added sensitivity of component-resolved diagnosis in hymenoptera venom-allergic patients with elevated serum tryptase and/or mastocytosis

Evolution Toward Chip-Based Arrays in the Laboratory Diagnosis of Human Allergic Disease

Multiplex-based specific IgE antibody assays have emerged into the clinical immunology laboratory through the combined use of pure, recombinant allergenic molecules and new methods to simultaneously and accurately analyze specific IgE antibodies to hundreds of allergens. This review traces the historical development and examines outstanding questions related to the strengths and limitations of these new molecular allergen multipex technologies for the assessment of human allergic sensitization. Multiplexed technologies are poised to provide the most cost-effective and comprehensive evaluation of patients with suspected allergy as compared with the commonly used singleplex autoanalyzers. How analytically sensitive and quantitative are the multiplex technologies, down to 0.1 kUA/L? Because each allergen is viewed as a unique assay, how will analytical and clinical performance be documented at the manufacturing and clinical laboratory levels to guarantee reproducibility and obtain government regulatory clearance? Will interference by naturally occurring allergen-specific IgG compromise analytical performance? Successful resolution of these and other questions covered in this review will position multiplex technologies to become the single most-effective means of screening patients for allergic sensitization, assessing IgE antibody cross-reactivity, and planning therapy directed at the patient with allergy.

Updates and Recent Advances on Venom Immunotherapy

Purpose of Review

Venom immunotherapy has been utilized to treat Hymenoptera venom allergy since the 1920s. Over the last century, significant advances in the fields of immunology and genetics have led to improvements in the practice of venom immunotherapy. This review encompasses recent advances in the use of venom immunotherapy to provide precise, patient-centered care.

Recent Findings

Research about the mechanism of action of venom immunotherapy continues to highlight the modification of both the innate and adaptive immune systems. Molecular techniques have allowed for the identification of specific venom allergens to improve the diagnostic accuracy and safety of venom immunotherapy. Research continues to support the safety of accelerated schedules which can impact the cost, adherence, and quality of life for patients receiving this treatment modality. Finally, significant advances have led to the elucidation of risk factors that place patients at risk for reactions during and after venom immunotherapy. Creation of risk profiles for venom-allergic patients can thus inform the process of immunotherapy in order to provide personalized and precise care.

Summary

Significant progress in the use of venom immunotherapy makes the practice a dynamic and active field for continued research. Future research needs to build on these recent advances to continue to optimize and enhance this life-saving treatment.

EAACI Molecular Allergology User's Guide 2.0

Since the discovery of immunoglobulin E (IgE) as a mediator of allergic diseases in 1967, our knowledge about the immunological mechanisms of IgE-mediated allergies has remarkably increased. In addition to understanding the immune response and clinical symptoms, allergy diagnosis and management depend strongly on the precise identification of the elicitors of the IgE-mediated allergic reaction. In the past four decades, innovations in bioscience and technology have facilitated the identification and production of well-defined, highly pure molecules for component-resolved diagnosis (CRD), allowing a personalized diagnosis and management of the allergic disease for individual patients. The first edition of the "EAACI Molecular Allergology User's Guide" (MAUG) in 2016 rapidly became a key reference for clinicians, scientists, and interested readers with a background in allergology, immunology, biology, and medicine. Nevertheless, the field of molecular allergology is moving fast, and after 6 years, a new EAACI Taskforce was established to provide an updated document. The Molecular Allergology User's Guide 2.0 summarizes state-of-the-art information on allergen molecules, their clinical relevance, and their application in diagnostic algorithms for clinical practice. It is designed for both, clinicians and scientists, guiding health care professionals through the overwhelming list of different allergen molecules available for testing. Further, it provides diagnostic algorithms on the clinical relevance of allergenic molecules and gives an overview of their biology, the basic mechanisms of test formats, and the application of tests to measure allergen exposure.

Diagnosis of Hymenoptera Venom Allergy: State of the Art, Challenges, and Perspectives

Hymenoptera venom allergy is the most common cause of anaphylaxis in adults and the second-most frequent in children. The proper diagnosis of this life-threatening allergy remains a challenge. This review focuses on the current knowledge regarding diagnostics of Hymenoptera venom allergy. The paper includes a brief description of the representatives of Hymenoptera order and the composition of their venoms. Then, diagnostic tests for allergy to Hymenoptera venom are described. Common diagnostic problems, especially double positivity in tests for IgE antibodies specific to honeybee and wasp venom, are also discussed. Special attention is paid to the search for new diagnostic capabilities using modern methodologies. Multidimensional molecular analysis offers an opportunity to characterize changes in body fluids associated with Hymenoptera venom allergy and yields a unique insight into the cell status. Despite recent developments in the diagnostics of Hymenoptera venom allergy, new testing methodologies are still needed to answer questions and doubts we have.

Refined Treatment Response Criteria for Indolent Systemic Mastocytosis Proposed by the ECNM-AIM Consortium

Indolent systemic mastocytosis (ISM) has a favorable prognosis and normal life expectancy. However, many patients suffer from mast cell (MC) mediator-related symptoms, which significantly affect quality of life (QoL). Cutaneous, gastrointestinal, and neurological complaints, musculoskeletal pain, and the presence of skin lesions, anaphylaxis, and osteoporosis are the main symptoms and signs in ISM and must be assessed in all patients before and during treatment. Validated mastocytosis-specific patient-reported outcome measures (PROMs) should be used for this purpose. Serum tryptase and KIT D816V allele burden are recommended as secondary outcome parameters, noting that they do not reflect the severity of signs, symptoms, and related QoL impairment, but indirectly express MC burden. Changes from baseline of 90%, 60%, and 30% indicate complete response >90%, major response 60% to 90%, partial response 30% to 60%, and no response <30% to treatment. To conclude, we recommend the use of PROMs as primary outcome parameters to define treatment response in patients with ISM in clinical trials and in everyday clinical practice.

Component-Resolved Evaluation of the Risk and Success of Immunotherapy in Bee Venom Allergic Patients

Venom immunotherapy (VIT) is the only efficient therapy for the Hymenoptera insect venom allergy. Immunotherapy with bee venom is encumbered with a higher risk of systemic side effects and/or therapeutic failures. The objective of the study was to assess if specific profiles of molecular IgE (Immunoglobulin E) responses are associated with an increased risk of systemic side effects and/or the treatment’s inefficacy. The study group numbered 64 bee venom allergic patients (BVA) who received venom immunotherapy modo ultra-rush (VIT-UR), (f/m: 32/32, mean age 43.4 ± 17.2). In total, 54.84% of them manifested allergic reactions of grades I-III (acc. to Mueller’s scale), while 48.66% manifested reactions of grade IV. In all the patients, IgE against bee venom extract, rApi m 1 and tryptase (sBT) were assessed. In 46 patients, assessments of IgE against rApi m 2, 3, 5, 10 were also performed. BVA patients manifesting cardiovascular symptoms (SYS IV0) showed higher levels of both sIgE-rApi m 5 (p = 0.03) and tryptase (p = 0.07) than patients with SYS I−III. Systemic adverse events during VIT with bee venom were more frequent in the induction phase than in the maintenance phase: 15.22% vs. 8.7%. In BVA patients who experienced systemic adverse events during VIT, higher concentrations of sIgE-rApi m 5 (p < 0.05), rApi m 1 (p = 0.009), and sBT (p = 0.019) were demonstrated. We conclude that higher levels of sIgE against rApi m 1, rApi m 5, and tryptase many constitute a potential marker of the severity of allergic reactions and therapeutic complications that can occur during VIT with bee venom.

Precision medicine in the allergy clinic: the application of component resolved diagnosis

INTRODUCTION

A precise diagnosis is key for the optimal management of allergic diseases and asthma. In vivo or in vitro diagnostic methods that use allergen extracts often fail to identify the molecules eliciting the allergic reactions.

AREAS COVERED

Component-resolved diagnosis (CRD) has solved most of the limitations of extract-based diagnostic procedures and is currently valuable tool for the precision diagnosis in the allergy clinic, for venom and food allergy, asthma, allergic rhinitis, and atopic dermatitis. Its implementation in daily practice facilitates: a) the distinction between genuine multiple sensitizations and cross-reactive sensitization in polysensitized patients; b) the prediction of a severe, systemic reaction in food or insect venom allergy; c) the optimal selection of allergen immunotherapy based on the patient sensitization profile. This paper describes its main advantages and disadvantages, cost-effectiveness and future perspectives.

EXPERT OPINION

The diagnostic strategy based on CRD is part of the new concept of precision immunology, which aims to improve the management of allergic diseases.

Molecular allergology and its impact in specific allergy diagnosis and therapy

Progressive knowledge of allergenic structures resulted in a broad availability of allergenic molecules for diagnosis. Component-resolved diagnosis allowed a better understanding of patient sensitization patterns, facilitating allergen immunotherapy decisions. In parallel to the discovery of allergenic molecules, there was a progressive development of a regulation framework that affected both in vitro diagnostics and Allergen Immunotherapy products. With a progressive understanding of underlying mechanisms associated to Allergen immunotherapy and an increasing experience of application of molecular diagnosis in daily life, we focus in analyzing the evidences of the value provided by molecular allergology in daily clinical practice, with a focus on Allergen Immunotherapy decisions.

Anaphylaxis to Stinging Insect Venom

Hymenoptera stinging insects are common culprits for allergic reactions. Anaphylaxis to insect stings can be life threatening and is associated with a significant risk of recurrence. Insect allergy requires referral to an allergist/immunologist for education and for diagnostic evaluation that will direct further management and treatment. Venom immunotherapy is safe and effective; it prevents sting anaphylaxis in up to 98% of patients. Potential risk factors for side effects during testing and treatment should be assessed for every patient to mitigate risk and to guide treatment recommendations and the duration of immunotherapy.

Systemic Mastocytosis: Multidisciplinary Approach

Systemic mastocytosis (SM) is a heterogeneous group of diseases that affect almost exclusively adults and are defined by the proliferation and accumulation of clonal mast cells (MC) in various tissues. Disease subtypes range from indolent to rare aggressive forms. Although SM is classified as a rare disease, it is believed to be likely underdiagnosed. Major signs and symptoms mainly depend on MC activation and less frequent organ infiltration, typical of more aggressive variants. Diagnosis may be challenging, and symptoms can be aspecific and involve several organs. Therefore, it is advisable to refer patients to specialized centers, having sufficient knowledge of the disease, sensitive diagnostic procedures, offering a personalized and multidisciplinary diagnostic approach, including at least hematological, allergological, dermatological, and rheumatological evaluations. A precise and timely diagnosis is required for: a) adequate counseling of patients and their physicians; b) beginning of symptomatic treatment (anti-mediator therapy); c) prevention of severe manifestations of the disease (i.e., recurrent anaphylaxis, osteoporosis, and bone fractures); d) cytoreductive treatment of advanced SM variants. This review summarizes the disease's main manifestations and describes the ideal diagnostic approach for adult patients with suspected SM, giving physicians the main notions for correct patient diagnosis and management. This review also highlights the importance of a multidisciplinary approach in this very complex disease.

Venom immunotherapy in indolent systemic mastocytosis with high serum tryptase level

Mastocytosis is a rare group of disorders characterized by abnormal accumulation of mast cells in the skin, bone marrow, and internal organs. In particular, patients with systemic mastocytosis are at an increased risk of frequent and severe episodes of anaphylaxis. Hymenoptera venom allergy is the most common trigger of anaphylaxis in these patients. Immunotherapy is an effective and safe therapy recommended for patients with mastocytosis and venom allergy. Although this therapy can be administered according to different protocols, the preferred protocol for patients with mastocytosis remains unclear. Systemic side effects can occur, in particular, during the up-dosing phase of immunotherapy, making progression to the maintenance phase of therapy challenging. This case report presents the diagnosis and ultrarush immunotherapy process ended with anaphylaxis of a 33-y-old male patient with Apis mellifera allergy.

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.

The role of component-resolved diagnosis in Hymenoptera venom allergy

PURPOSE OF REVIEW

Component-resolved diagnostics (CRD) is a new tool aiming at detecting IgE-mediated sensitizations against individual, relevant allergens. Here, we discuss recent literature on molecular diagnosis in the field of Hymenoptera venom allergy (HVA) as well as CRD strengths and weaknesses.

RECENT FINDINGS

CRD, using single molecules or panels of allergens, may discriminate between primary sensitization and cross-reactivity in patients with double/multiple positivity in diagnostic tests with whole extracts, allowing the specialist to choose the most suitable venom for specific immunotherapy (VIT), avoiding unnecessary VIT and reducing the risk of side effects. Future availability of the cross-reactive recombinant pairs of allergens of different species may further increase the diagnostic performance. CRD may be useful in patients with negative allergy tests and a proven history of a previous systemic reaction, including those with mast cell disorders, who could benefit from VIT. In honeybee venom allergy, different sensitization profiles have been identified, which could be associated with a greater risk of VIT failure or treatment side effects.

SUMMARY

CRD is undoubtedly an innovative diagnostic method that leads to a more precise definition of the sensitization profile of the HVA patient. Together with a better knowledge of the molecular composition of different venom extracts, CRD may contribute to optimize patient-tailored therapy.

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.

A WAO - ARIA - GA2LEN consensus document on molecular-based allergy diagnosis (PAMD@): Update 2020

Precision allergy molecular diagnostic applications (PAMD@) is increasingly entering routine care. Currently, more than 130 allergenic molecules from more than 50 allergy sources are commercially available for in vitro specific immunoglobulin E (sIgE) testing. Since the last publication of this consensus document, a great deal of new information has become available regarding this topic, with over 100 publications in the last year alone. It thus seems quite reasonable to publish an update. It is imperative that clinicians and immunologists specifically trained in allergology keep abreast of the new and rapidly evolving evidence available for PAMD@.

PAMD@ may initially appear complex to interpret; however, with increasing experience, the information gained provides relevant information for the allergist. This is especially true for food allergy, Hymenoptera allergy, and for the selection of allergen immunotherapy. Nevertheless, all sIgE tests, including PAMD@, should be evaluated within the framework of a patient's clinical history, because allergen sensitization does not necessarily imply clinical relevant allergies.

Risk factors and indicators of severe systemic insect sting reactions

Hymenoptera venom allergy ranks among the top three causes of anaphylaxis worldwide, and approximately one-quarter of sting-induced reactions are classified as severe. Fatal sting reactions are exceedingly rare, but certain factors may entail a considerably higher risk. Delayed administration of epinephrine and upright posture are situational risk factors which may determine an unfavorable outcome of the acute anaphylactic episode and should be addressed during individual patient education. Systemic mastocytosis and senior age are major, unmodifiable long-term risk factors and thus reinforce the indication for venom immunotherapy. Vespid venom allergy and male sex likewise augment the risk of severe or even fatal reactions. Further studies are required to assess the impact of specific cardiovascular comorbidities. Available data regarding potential effects of beta-blockers and/or ACE inhibitors in coexisting venom allergy are inconclusive and do not justify recommendations to discontinue guideline-directed antihypertensive treatment. The absence of urticaria/angioedema during sting-induced anaphylaxis is indicative of a severe reaction, serum tryptase elevation, and mast cell clonality. Determination of basal serum tryptase levels is an established diagnostic tool for risk assessment in Hymenoptera venom-allergic patients. Measurement of platelet-activating factor acetylhydrolase activity represents a complementary approach but is not available for routine diagnostic use.

Allergy and sensitization to Hymenoptera venoms in unreferred adults with a high risk of sting exposure

Background

Hymenoptera venom sensitization in highly exposed individuals frequently requires risk assessment for future severe sting reactions. In this study, we determined the prevalence of Hymenoptera venom sensitization in individuals who hunt and fish and analyzed possible correlations between the severity of sting reactions and the IgE sensitization profile.

Methods

In this cross-sectional study, paper-based, self-filled questionnaires about previous insect stings and sting reactions were obtained from individuals who hunt and fish in Bavaria, Germany. Blood samples were taken and analyzed for the levels of tryptase, total IgE and IgE to honey bee (i1) and wasp (13) venom, the recombinant allergens rApi m 1, rApi m 2, rApi m 3, rApi m 5, rApi m 10, rVes v 1, rVes v 5, and the CCD marker molecule MUXF3. Odd ratios (ORs) for sensitization and anaphylaxis and Pearson's correlations for the different allergens were calculated.

Results

Of 257 participants, 50.2% showed a sensitization to honey bee venom (i1), and 58.4% showed sensitization to wasp venom (i3). A total of 98.4% of participants claimed to have been stung at least once. Anaphylaxis was reported in 18.7%, and a local sting reaction was reported in 18.3%. The highest sensitization rates were found for whole venom extracts, sensitization to any of the available recombinant allergens exceeded sIgE levels to honeybee venom (i1) in 28.5% and to wasp venom (i3) in 52.9% of participants. Participants with a history of more than 5 stings showed a higher risk for anaphylaxis.

Conclusions

Sensitization to Hymenoptera venom and their recombinant allergens are present in the majority of individuals who hunt and fish. Sensitization to distinct recombinant allergens does not necessarily affect the severity of sting reactions including anaphylaxis. A meticulous medical history of the number of previous stings as well as systemic reactions remains essential.

Adverse reactions to drugs and biologics in patients with clonal mast cell disorders: A Work Group Report of the Mast Cells Disorder Committee, American Academy of Allergy, Asthma & Immunology

Providers caring for patients with mastocytosis are tasked with the decision to consider therapeutic options. This can come with some trepidation because information available in the public domain lists numerous mast cell (MC) activators based on data that do not discriminate between primates, rodents, and MC lines; do not consider dosage; and do not take into account previous exposure and resultant clinical findings. This being said, there is support in the literature for an enhanced MC response in some patients with mastocytosis and in cases in which there is a greater incidence of adverse reactions associated with certain antigens, such as venoms and drugs. Thus this report provides a comprehensive guide for those providers who must decide on therapeutic options in the management of patients with clonal MC disease.

Component-resolved diagnostics to direct in venom immunotherapy: Important steps towards precision medicine

Stings of Hymenoptera can induce IgE-mediated systemic and even fatal allergic reactions. Venom-specific immunotherapy (VIT) is the only disease-modifying and curative treatment of venom allergy. However, choosing the correct venom for VIT represents a necessary prerequisite for efficient protection against further anaphylactic sting reactions after VIT. In the past, therapeutic decisions based on the measurement of specific IgE (sIgE) levels to whole venom extracts were not always straightforward, especially when the patient was not able to identify the culprit insect. In the last years, the increasing knowledge about the molecular structure and relevance of important venom allergens and their availability as recombinant allergens, devoid of cross-reactive carbohydrate determinants, resulted in the development of an advanced component-resolved diagnostics (CRD) approach in venom allergy. Already to date, CRD has increased the sensitivity of sIgE detection and enabled the discrimination between primary sensitization and cross-reactivity, particularly in patients with sensitization to both honeybee and vespid venom. Hence, CRD in many patients improves the selection of the appropriate immunotherapeutic intervention. Moreover, the detailed knowledge about sensitization profiles on a molecular level might open new options to identify patients who are at increased risk of side-effects or not to respond to immunotherapy. Therefore, increasing potential of CRD becomes evident, to direct therapeutic decisions in a personalized and patient-tailored manner. Reviewed here are the state of the art options, recent developments and future perspectives of CRD of Hymenoptera venom allergy.

Advances in environmental and occupational disorders in 2016

In this review we highlight recent studies that advance the knowledge and understanding of the effects of various environmental factors and associated immune responses in patients with allergic diseases. This review will focus on new literature regarding allergic and immune responses to a variety of environmental factors, including aeroallergens, stinging insects, fungi, pollutants, viral respiratory tract infections, climate change, and microbial exposures.

Component Resolved Diagnosis in Hymenoptera Anaphylaxis

PURPOSE OF REVIEW

Hymenoptera anaphylaxis is one of the leading causes of severe allergic reactions and can be fatal. Venom-specific immunotherapy (VIT) can prevent a life-threatening reaction; however, confirmation of an allergy to a Hymenoptera venom is a prerequisite before starting such a treatment. Component resolved diagnostics (CRD) have helped to better identify the responsible allergen.

RECENT FINDINGS

Many new insect venom allergens have been identified within the last few years. Commercially available recombinant allergens offer new diagnostic tools for detecting sensitivity to insect venoms. Additional added sensitivity to nearly 95% was introduced by spiking yellow jacket venom (YJV) extract with Ves v 5. The further value of CRD for sensitivity in YJV and honey bee venom (HBV) allergy is more controversially discussed. Recombinant allergens devoid of cross-reactive carbohydrate determinants often help to identify the culprit venom in patients with double sensitivity to YJV and HBV. CRD identified a group of patients with predominant Api m 10 sensitization, which may be less well protected by VIT, as some treatment extracts are lacking this allergen. The diagnostic gap of previously undetected Hymenoptera allergy has been decreased via production of recombinant allergens. Knowledge of analogies in interspecies proteins and cross-reactive carbohydrate determinants is necessary to distinguish relevant from irrelevant sensitizations.

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.

Precision medicine in allergic disease-food allergy, drug allergy, and anaphylaxis-PRACTALL document of the European Academy of Allergy and Clinical Immunology and the American Academy of Allergy, Asthma and Immunology

This consensus document summarizes the current knowledge on the potential for precision medicine in food allergy, drug allergy, and anaphylaxis under the auspices of the PRACTALL collaboration platform. PRACTALL is a joint effort of the European Academy of Allergy and Clinical Immunology and the American Academy of Allergy, Asthma and Immunology, which aims to synchronize the European and American approaches to allergy care. Precision medicine is an emerging approach for disease treatment based on disease endotypes, which are phenotypic subclasses associated with specific mechanisms underlying the disease. Although significant progress has been made in defining endotypes for asthma, definitions of endotypes for food and drug allergy or for anaphylaxis lag behind. Progress has been made in discovery of biomarkers to guide a precision medicine approach to treatment of food and drug allergy, but further validation and quantification of these biomarkers are needed to allow their translation into practice in the clinical management of allergic disease.

ImmunoCAP cellulose displays cross-reactive carbohydrate determinant (CCD) epitopes and can cause false-positive test results in patients with high anti-CCD IgE antibody levels

BACKGROUND

Cross-reactive carbohydrate determinants (CCDs) in plants and insect venoms are a common cause of irrelevant positive test results during in vitro allergy diagnosis. We observed that some CCD-positive sera show nonspecific IgE binding even with CCD-free recombinant allergens when using the Phadia ImmunoCAP platform.

OBJECTIVE

We investigated whether cellulose used as an allergen carrier in ImmunoCAP harbors residual N-glycans, causing nonspecific background binding in CCD-positive sera.

METHODS

IgE binding to 6 samples of blank ImmunoCAPs coupled to either streptavidin (SA-CAP-1 or 2) or nonallergenic maltose-binding protein (MBP; MBP-CAP-1 to 4) and binding to a panel of 4 recombinant allergens were compared in CCD-positive sera before and after inhibition with a CCD inhibitor (MUXF³-human serum albumin).

RESULTS

Of 52 CCD-positive sera (bromelain, 1.01-59.6 kilounits of antigen per liter [kU_A/L]) tested on SA-CAP-1, 35 (67%) showed IgE binding of greater than 0.35 kU_A/L (0.41-4.22 kU_A/L). Among those with anti-CCD IgE levels of greater than 7.0 kU_A/L, 90% (26/29) were positive. IgE binding to SA-CAP-1 correlated with IgE binding to bromelain (r = 0.68) and was completely abolished by serum preincubation with the CCD inhibitor (n = 15). Binding scores with SA-CAP-2 and MBP-CAP-1 to MBP-CAP-4 were generally lower but strongly correlated with those of SA-CAP-1 and bromelain. IgE reactivity of 10 CCD-positive sera (14.0-52.5 kU_A/L) with the recombinant allergens rPhl p 12, rFel d 1, rAra h 2, and rPru p 3 was positive to at least 1 allergen in 8 of 10 (0.36-1.63 kU_A/L) and borderline in 2 of 10 (0.21-0.25 kU_A/L). Binding correlated with antibody binding to bromelain (r = 0.61) and to all blank ImmunoCAPs (r > 0.90) and could be completely blocked by the CCD inhibitor. Overall, mean background binding to cellulose CCDs corresponded to 2% to 3% of the reactivity seen with bromelain.

CONCLUSIONS

Cellulose used as a solid-phase allergen carrier can contain varying amounts of CCDs sufficient to cause false-positive test results up to 2 kU_A/L with nonglycosylated recombinant allergens in patients with high levels of anti-CCD IgE antibodies.

Application of recombinant antigen 5 allergens from seven allergy-relevant Hymenoptera species in diagnostics

BACKGROUND

Hymenoptera stings can cause severe anaphylaxis in untreated venom-allergic patients. A correct diagnosis regarding the relevant species for immunotherapy is often hampered by clinically irrelevant cross-reactivity. In vespid venom allergy, cross-reactivity between venoms of different species can be a diagnostic challenge. To address immunological IgE cross-reactivity on molecular level, seven recombinant antigens 5 of the most important Vespoidea groups were assessed by different diagnostic setups.

METHODS

The antigens 5 of yellow jackets, hornets, European and American paper wasps, fire ants, white-faced hornets, and Polybia wasps were recombinantly produced in insect cells, immunologically and structurally characterized, and their sIgE reactivity assessed by ImmunoCAP, ELISA, cross-inhibition, and basophil activation test (BAT) in patients with yellow jacket or Polistes venom allergy of two European geographical areas.

RESULTS

All recombinant allergens were correctly folded and structural models and patient reactivity profiles suggested the presence of conserved and unique B-cell epitopes. All antigens 5 showed extensive cross-reactivity in sIgE analyses, inhibition assays, and BAT. This cross-reactivity was more pronounced in ImmunoCAP measurements with venom extracts than in sIgE analyses with recombinant antigens 5. Dose-response curves with the allergens in BAT allowed a differentiated individual dissection of relevant sensitization.

CONCLUSIONS

Due to extensive cross-reactivity in various diagnostic settings, antigens 5 are inappropriate markers for differential sIgE diagnostics in vespid venom allergy. However, the newly available antigens 5 from further vespid species and the combination of recombinant allergen-based sIgE measurements with BAT represents a practicable way to diagnose clinically relevant sensitization in vespid venom allergy.

Mastocytosis and Anaphylaxis

This article updates current knowledge on epidemiology, risk factors, triggers, and management of anaphylaxis in patients with mastocytosis. Hyperactive mast cells and higher number of effector mast cells are speculated to facilitate anaphylaxis in this condition. In children, increased risk is limited to those with extensive skin involvement and high tryptase. In adults, manifestations of anaphylaxis are severe with high frequency of cardiovascular symptoms. Hymenoptera stings are the most common triggers for these reactions; however, idiopathic anaphylaxis and reactions to food or drugs occur. Patients with mastocytosis should be informed about risk of anaphylaxis and prescribing emergency self-medication and installing emergency preparedness before general anesthesia is considered.