Basophil activation test: Mechanisms and considerations for use in clinical trials and clinical practice

Increased expression of formyl peptide receptor-1 by basophils from patients with mastocytosis

Background

Symptoms in patients with systemic mastocytosis (SM) are associated with an increase in mast cell burden and release of mast cell-derived mediators. The most frequent presentation of SM is indolent SM (ISM), with moderate symptoms and prognosis. Basophil numbers in these patients are generally normal. However, when examining basophil activation in patients with ISM, we noted an abnormal response to N-formylmethione-leucyl-phenylalanine (fMLP).

Objective

Our aim was to compare basophil responsiveness to fMLP and anti-IgE in healthy volunteers and patients with ISM and relate the findings to fMLP receptor (FPR) expression.

Methods

Basophils isolated from peripheral blood of 15 patients with ISM and 14 healthy volunteers were stimulated with fMLP or anti-IgE. CD63 expression to assess basophil activation and expression of FPRs were assessed by flow cytometry.

Results

Baseline expression of CD63 on basophils was similar between the healthy volunteers and patients with ISM. fMLP induced higher expression of CD63 on basophils from patients with ISM, whereas responses to anti-IgE were similar between groups. Basophils from patients with ISM also had higher fMLP1 receptor (FPR1) expression, wheresas FPR2 and FPR3 were not detected. fMLP blocked the binding of anti-FPR1 antibody to FPR1, consistent with the conclusion that fMLP signals through FPR1.

Conclusions

Level of fMLP-induced basophil activation is higher in patients with ISM, which is associated with an increase in FPR1 expression. Further investigation is needed to determine why FPR1 expression is elevated, whether such expression might serve as an additional surrogate marker in the diagnosis of ISM, and whether enhanced responses of basophils to fMPL might have some relationship to unexplained episodes of mediator release.

Extracellular vesicles from the microalga Tetraselmis chuii are biocompatible and exhibit unique bone tropism along with antioxidant and anti-inflammatory properties

Extracellular vesicles (EVs) are membrane-enclosed bio-nanoparticles secreted by cells and naturally evolved to transport various bioactive molecules between cells and even organisms. These cellular objects are considered one of the most promising bio-nanovehicles for the delivery of native and exogenous molecular cargo. However, many challenges with state-of-the-art EV-based candidates as drug carriers still exist, including issues with scalability, batch-to-batch reproducibility, and cost-sustainability of the final therapeutic formulation. Microalgal extracellular vesicles, which we named nanoalgosomes, are naturally released by various microalgal species. Here, we evaluate the innate biological properties of nanoalgosomes derived from cultures of the marine microalgae Tetraselmis chuii, using an optimized manufacturing protocol. Our investigation of nanoalgosome biocompatibility in preclinical models includes toxicological analyses, using the invertebrate model organism Caenorhabditis elegans, hematological and immunological evaluations ex vivo and in mice. We evaluate nanoalgosome cellular uptake mechanisms in C. elegans at cellular and subcellular levels, and study their biodistribution in mice with accurate space-time resolution. Further examination highlights the antioxidant and anti-inflammatory bioactivities of nanoalgosomes. This holistic approach to nanoalgosome functional characterization demonstrates that they are biocompatible and innate bioactive effectors with unique bone tropism. These findings suggest that nanoalgosomes have significant potential for future therapeutic applications.

Prediction of pediatric peanut oral food challenge outcomes using machine learning

Background

Clinical testing, including food-specific skin and serum IgE level tests, provides limited accuracy to predict food allergy. Confirmatory oral food challenges (OFCs) are often required, but the associated risks, cost, and logistic difficulties comprise a barrier to proper diagnosis.

Objective

We sought to utilize advanced machine learning methodologies to integrate clinical variables associated with peanut allergy to create a predictive model for OFCs to improve predictive performance over that of purely statistical methods.

Methods

Machine learning was applied to the Learning Early about Peanut Allergy (LEAP) study of 463 peanut OFCs and associated clinical variables. Patient-wise cross-validation was used to create ensemble models that were evaluated on holdout test sets. These models were further evaluated by using 2 additional peanut allergy OFC cohorts: the IMPACT study cohort and a local University of Michigan cohort.

Results

In the LEAP data set, the ensemble models achieved a maximum mean area under the curve of 0.997, with a sensitivity and specificity of 0.994 and 1.00, respectively. In the combined validation data sets, the top ensemble model achieved a maximum area under the curve of 0.871, with a sensitivity and specificity of 0.763 and 0.980, respectively.

Conclusions

Machine learning models for predicting peanut OFC results have the potential to accurately predict OFC outcomes, potentially minimizing the need for OFCs while increasing confidence in food allergy diagnoses.

Targeting inhibitory Siglec-3 to suppress IgE-mediated human basophil degranulation

BACKGROUND

Sialic acid-binding immunoglobulin-like lectin-3 (Siglec-3 [CD33]) is a major Siglec expressed on human mast cells and basophils; engagement of CD33 leads to inhibition of cellular signaling via immunoreceptor tyrosine-based inhibitory motifs.

OBJECTIVE

We sought to inhibit human basophil degranulation by simultaneously recruiting inhibitory CD33 to the IgE-FcεRI complex by using monoclonal anti-IgE directly conjugated to CD33 ligand (CD33L).

METHODS

Direct and indirect basophil activation tests (BATs) were used to assess both antigen-specific (peanut) and antigen-nonspecific (polyclonal anti-IgE) stimulation. Whole blood from donors with allergy was used for direct BAT, whereas blood from donors with nonfood allergy was passively sensitized with plasma from donors with peanut allergy in the indirect BAT. Blood was incubated with anti-IgE-CD33L or controls for 1 hour or overnight and then stimulated with peanut, polyclonal anti-IgE, or N-formylmethionyl-leucyl-phenylalanine for 30 minutes. Degranulation was determined by measuring CD63 expression on the basophil surface by flow cytometry.

RESULTS

Incubation for 1 hour with anti-IgE-CD33L significantly reduced basophil degranulation after both allergen-induced (peanut) and polyclonal anti-IgE stimulation, with further suppression after overnight incubation with anti-IgE-CD33L. As expected, anti-IgE-CD33L did not block basophil degranulation due to N-formylmethionyl-leucyl-phenylalanine, providing evidence that this inhibition is IgE pathway-specific. Finally, CD33L is necessary for this suppression, as monoclonal anti-IgE without CD33L was unable to reduce basophil degranulation.

CONCLUSIONS

Pretreating human basophils with anti-IgE-CD33L significantly suppressed basophil degranulation through the IgE-FcεRI complex. The ability to abrogate IgE-mediated basophil degranulation is of particular interest, as treatment with anti-IgE-CD33L before antigen exposure could have broad implications for the treatment of food, drug, and environmental allergies.

Rapid generation of an RBL cellular model to study proteins that cause allergenic reactions in vitro

Allergic diseases affect nearly 30% of people worldwide. There is a wide range of allergen sources, such as animal dander, food, venom, dust mites, and pollen. The skin prick test is the predominant technique used to identify allergenic sensitivity in vivo; the main problem is that it can be imprecise as many of the allergen extracts are made of mixtures of allergic and nonallergic components, making it difficult to identify the disease-eliciting allergen. An alternative to solve this problem is employing cellular models in vitro that may allow allergen identification, allergy diagnosis, and testing of novel potential compounds that can be used in immunotherapeutics. For example, rat basophilic leukemia (RBL) cells are a well-suited model for studying allergies. Unfortunately, cells generated from RBL cells are not commercially available. Therefore, we developed an RBL model with a degranulation gene reporter capable of recognizing human IgE involved in allergenic sensitivity using commercial plasmids. Employing this model, we successfully evaluated the capacity of union between IgE from allergic patients to allergenic proteins from Oleaceae tree pollen. This RBL cell model can be used as a diagnostic method for sensitivity to any allergens from different sources in vitro.

Granulocytes and mast cells in AllergoOncology-Bridging allergy to cancer: An EAACI position paper

Derived from the myeloid lineage, granulocytes, including basophils, eosinophils, and neutrophils, along with mast cells, play important, often disparate, roles across the allergic disease spectrum. While these cells and their mediators are commonly associated with allergic inflammation, they also exhibit several functions either promoting or restricting tumor growth. In this Position Paper we discuss common granulocyte and mast cell features relating to immunomodulatory functions in allergy and in cancer. We highlight key mechanisms which may inform cancer treatment and propose pertinent areas for future research. We suggest areas where understanding the communication between granulocytes, mast cells, and the tumor microenvironment, will be crucial for identifying immune mechanisms that may be harnessed to counteract tumor development. For example, a comprehensive understanding of allergic and immune factors driving distinct neutrophil states and those mechanisms that link mast cells with immunotherapy resistance, might enable targeted manipulation of specific subpopulations, leading to precision immunotherapy in cancer. We recommend specific areas of investigation in AllergoOncology and knowledge exchange across disease contexts to uncover pertinent reciprocal functions in allergy and cancer and allow therapeutic manipulation of these powerful cell populations. These will help address the unmet needs in stratifying and managing patients with allergic diseases and cancer.

Clinical investigation for the mechanisms of anaphylactic symptoms in osteoarthritis patients after diclofenac etalhyaluronate administration

OBJECTIVE

This study was conducted to investigate the mechanisms of anaphylaxis in patients with osteoarthritis of the knee and hip after diclofenac etalhyaluronate [product name: JOYCLU® (JCL)] intra-articular injection and to determine the utility of tests to investigate the mechanism involved.

METHODS

In this observational study in Japan, patients aged ≥20 years with knee or hip osteoarthritis who received JCL intra-articular injection experienced anaphylactic symptoms considered related to JCL ('experienced patients') or did not experience allergic symptoms considered related to JCL ('non-experienced patients'). Basophil activation tests (BATs), specific immunoglobulin E (IgE) antibody testing by enzyme-linked immunosorbent assays (ELISAs) or immunochromatographic kit, and genome-wide association studies (GWASs) were conducted using patient blood and saliva.

RESULTS

Thirteen experienced patients and 14 non-experienced patients were tested. Seven experienced patients tested positive by BAT using diclofenac etalhyaluronate-containing test substances. Diclofenac-specific IgE antibodies were detected in four of seven BAT-positive patients but not in the non-experienced patients. Specific IgE antibody testing by immunochromatographic kit and genome-wide association study showed no clear results.

CONCLUSIONS

These findings suggest that anaphylaxis occurs after JCL administration via an IgE-mediated mechanism and that diclofenac etalhyaluronate may be involved in this mechanism. BAT and diclofenac -specific IgE enzyme-linked immunosorbent assay may be useful tests for investigating the mechanisms of anaphylactic reactions after JCL administration.

New developments in biotechnology applied to microorganisms

EFSA was requested by the European Commission (in accordance with Article 29 of Regulation (EC) No 178/2002) to provide a scientific opinion on the application of new developments in biotechnology (new genomic techniques, NGTs) to viable microorganisms and products of category 4 to be released into the environment or placed on the market as or in food and feed, and to non-viable products of category 3 to be placed on the market as or in food and feed. A horizon scanning exercise identified a variety of products containing microorganisms obtained with NGTs (NGT-Ms), falling within the remit of EFSA, that are expected to be placed on the (EU) market in the next 10 years. No novel potential hazards/risks from NGT-Ms were identified as compared to those obtained by established genomic techniques (EGTs), or by conventional mutagenesis. Due to the higher efficiency, specificity and predictability of NGTs, the hazards related to the changes in the genome are likely to be less frequent in NGT-Ms than those modified by EGTs and conventional mutagenesis. It is concluded that EFSA guidances are 'partially applicable', therefore on a case-by-case basis for specific NGT-Ms, fewer requirements may be needed. Some of the EFSA guidances are 'not sufficient' and updates are recommended. Because possible hazards relate to genotypic and phenotypic changes introduced and not to the method used for the modification, it is recommended that any new guidance should take a consistent risk assessment approach for strains/products derived from or produced with microorganisms obtained with conventional mutagenesis, EGTs or NGTs.

Basophil activation test in the diagnostic workup of perioperative anaphylaxis due to neuromuscular blocking agents: A case series and implications for practice

In Australia, neuromuscular blocking agents are the leading cause of perioperative anaphylaxis. Current investigation of suspected anaphylaxis includes tryptase levels, serum immunoglobulin E (IgE) levels, and skin testing, including intradermal testing and skin prick testing. The gold standard for the diagnosis of a hypersensitivity reaction is a challenge test, but this poses a risk to patient safety. An alternative test, known as the basophil activation test (BAT) is a form of cellular in vitro testing using flow cytometry to measure the degree of basophil degranulation within a sample of blood following exposure to an allergen. This acts as a surrogate marker for mast cell and basophil activation, thereby identifying IgE-mediated allergy. It is most commonly used to supplement equivocal findings from initial in vitro testing to assist in confirming the diagnosis of a hypersensitivity reaction and identify the causative agent. We present a case series in which five patients with suspected anaphylaxis underwent a BAT, demonstrating its role and limitations in allergy testing within Australia.

Oral Immunotherapy: An Overview

Oral immunotherapy (OIT) is an alternative treatment of IgE-mediated food allergy that has been shown to increase tolerance threshold to many of the top food allergens, although this effect may be dependent on age, dose, frequency, and duration. OIT has been shown to be effective and safe in infants, and early initiation can improve rates of desensitization even for those foods whose natural history favors loss of allergy. Studies looking at protocol modification to improve OIT success are ongoing as is the evaluation of clinical tools to help monitor OIT effects.

Treatment of Allergies to Fur Animals

Allergy to fur animals is becoming an increasingly common clinical problem in everyday medical practice. Depending on the route of exposure to the allergen, patients present with many, often non-specific symptoms. The most common illnesses among people with allergies to the above-mentioned allergens are as follows: allergic rhinitis, allergic conjunctivitis, atopic bronchial asthma, food allergy, allergic contact dermatitis, and sometimes anaphylactic shock. In recent years, there has been a change in the holistic approach to the treatment of allergy patients. The method of treatment should be tailored to a specific patient, taking into account his or her predispositions, economic possibilities, and therapeutic goals. The article describes the main methods of treating allergies, focusing primarily on allergies to fur animals. Allergy treatment always requires great care, and qualification for specific types of therapy should be preceded by a thorough and accurate diagnosis.

BASOPHILS ACTIVATE PRURICEPTOR-LIKE VAGAL SENSORY NEURONS

Vagal sensory neurons convey sensations from internal organs along the vagus nerve to the brainstem. Pruriceptors are a subtype of neurons that transmit itch and induce pruritus. Despite extensive research on the molecular mechanisms of itch, studies focusing on pruriceptors in the vagal ganglia still need to be explored. In this study, we characterized vagal pruriceptor neurons by their responsiveness to pruritogens such as lysophosphatidic acid, β-alanine, chloroquine, and the cytokine oncostatin M. We discovered that lung-resident basophils produce oncostatin M and that its release can be induced by engagement of FcεRIα. Oncostatin M then sensitizes multiple populations of vagal sensory neurons, including Tac1+ and MrgprA3+ neurons in the jugular ganglia. Finally, we observed an increase in oncostatin M release in mice sensitized to the house dust mite Dermatophagoides pteronyssinus or to the fungal allergen Alternaria alternata, highlighting a novel mechanism through which basophils and vagal sensory neurons may communicate during type I hypersensitivity diseases such as allergic asthma.

Serologic measurements for peanut allergy: Predicting clinical severity is complex

Allergist-immunologists use serologic peanut allergy testing to maximize test sensitivity and specificity while minimizing cost and inconvenience. Recent advances toward this goal include a better understanding of specific IgE (sIgE) and component testing, epitope-sIgE assays, and basophil activation testing. Predicting reaction severity with serologic testing is challenged by a range of co-factors that influence reaction severity, such as the amount and form of any allergen consumed and comorbid disease. In 2020, the Allergy Immunology Joint Task Force on Practice Parameters recommended Ara h 2-sIgE as the most cost-effective diagnostic test for peanut allergy because of its superior performance, when compared with skin prick testing and serum IgE. Basophil activation testing, a functional test of allergic response not evaluated in the Joint Task Force on Practice Parameters guideline, is a promising option for both allergy diagnosis and prognosis. Similarly, epitope-sIgE testing may improve prediction of reaction thresholds, but further validation is needed. Despite advances in food allergy testing, many of these tools remain limited by cost, accessibility, and feasibility. In addition, there is a need for further research on how atopic dermatitis may be modifying serologic food allergy severity assessments. Given these limitations, allergy test selection requires a shared decision-making approach so that a patient's values and preferences regarding financial impact, inconvenience, and psychological effects are considered in the context of clinician expertise on the timing and use of optimized testing.

Management of food allergy based on oral food challenge

PURPOSE OF REVIEW

Food allergy is a growing health problem that affects both patients and society in multiple ways. Despite the emergence of novel diagnostic tools, such as component-resolved diagnostics (CRD) and basophil activation tests (BAT), oral food challenge (OFC) still plays an indispensable role in the management of food allergies. This review aimed to highlight the indications and safety concerns of conducting an OFC and to provide insights into post-OFC management based on recent findings.

RECENT FINDINGS

Standardized OFC protocols have regional diversification, especially in Japan and Western countries. Recent studies suggested that the interval between doses should be at least more than an hour. Furthermore, applying a stepwise method tailored to the patient's specific immunoglobulin E level and history of anaphylaxis seems to mitigate these risks. Recent surveys have shown that, following a positive OFC, options other than strict avoidance are also selected.

SUMMARY

OFC serves diverse purposes, yet the risks it carries warrant caution. The stepwise protocol appears promising for its safety. Subthreshold consumption following OFC shows potential; however, further research on its efficacy and safety is required. Management following OFC should be tailored and well discussed between clinicians and patients.

Diagnostics of Allergy to Furry Animals-Possibilities in 2024

Diagnosing allergies is not always easy. Sometimes the symptoms reported by the patient do not match the results of diagnostic tests. Diagnostics of IgE-dependent allergy, including allergy to furry animals, can be based on two basic strategies, "BOTTOM-UP" and "TOP-DOWN", and almost all available allergy tests can be used ranging from skin tests, through specific IgE, to molecular panels and challenge tests. Currently, most information regarding the diagnosis and incidence of allergies to furry animals focuses almost exclusively on the two most common pets-dogs and cats. This is certainly due to the fact that allergy to cats and/or dogs is a common phenomenon, has a huge impact on quality of life, and is a challenge for doctors of many specialties. However, the growing number of owners of other pet species means that diagnostic methods must keep up with the changing needs of patients. Further research in these groups will certainly provide new facts and facilitate clinical decision-making when working with allergic patients.

Validation of the NUT CRACKER Diagnostic Algorithm and Prediction for Cashew and Pistachio Co-Allergy

BACKGROUND

Because of the high cross-sensitization among tree nuts, the NUT CRACKER (Nut Co-reactivity-Acquiring Knowledge for Elimination Recommendations) study proposed a diagnostic algorithm to minimize the number of required oral food challenges (OFCs).

OBJECTIVE

To validate the algorithm for cashew and pistachio allergy and determine markers for allergic severity.

METHODS

Patients (n = 125) with a median age of 7.8 (interquartile range, 5.9-11.2) years with suspected tree nut allergy were evaluated prospectively with decision tree points on the basis of skin prick test (SPT), basophil activation test (BAT), and knowledge of the coincidence of allergies. Validation of allergic status was determined by OFC. Markers of clinical severity were evaluated using the combined original and prospective cohort (n = 187) in relationship to SPT, BAT, and Ana o 3-sIgE.

RESULTS

Reactivity to cashew in SPT, BAT, and Ana o 3-sIgE and the incidence of abdominal pain on challenge were significantly higher in dual-allergic cashew/pistachio patients (n = 82) versus single cashew allergic patients (n = 18) (P = .001). All 3 diagnostic tests showed significant inverse correlation with log10 reaction doses for positive cashew OFC. The algorithm reduced overall the total number of OFCs by 72.0%, with a positive predictive value and negative predictive value of 93.0% and 99.0%, respectively. Cashew false-positives were observed primarily in hazelnut-allergic patients (P = .026). In this population, Ana o 3-specific IgE could diagnose cashew allergy with a sensitivity of more than 90% and a specificity of more than 95%.

CONCLUSIONS

The NUT CRACKER diagnostic algorithm was validated and reduced the number of diagnostic OFCs required. Markers for severity phenotypes may guide oral immunotherapy protocols, improving the risk/benefit ratio for patients.

Accurate determination of house dust mite sensitization in asthma and allergic rhinitis through cytometric detection of Der p 1 and Der p 2 binding on basophils (CytoBas)

BACKGROUND

House dust mite (HDM) is the most common allergen trigger globally for allergic rhinitis and atopic asthma.

OBJECTIVES

To expedite accurate confirmation of allergen sensitization, we designed fluorescent allergen tetramers to directly stain specific IgE on basophils to detect specific allergen sensitization using the flow cytometric CytoBas assay.

METHODS

Recombinant proteins of major HDM allergens (component), Der f 1, Der p 1, and Der p 2 were biotinylated and conjugated with fluorochrome streptavidins as tetramers. Blood samples from 64 patients who are HDM-allergic and 26 controls that are non-HDM-sensitized were incubated with allergen tetramers for evaluation of basophil binding (CytoBas) and activation (BAT) with flow cytometry.

RESULTS

The tetramers effectively bound and activated basophils from patients who are allergic but not from controls who are nonsensitized. CytoBas with Der p 1 as a single allergen had comparable sensitivity and specificity (92% and 100%) to BAT (91% and 100%) in detecting allergen sensitization, as did CytoBas with Der p 2 (95% and 96%) to BAT (95% and 87%). A positive staining for Der p 1 and/or Der p 2 in CytoBas was 100% sensitive and 96% specific for HDM allergy.

CONCLUSIONS

CytoBas has diagnostic accuracy for group 1 and group 2 HDM allergens that is comparable to BAT, but with additional advantages of multiple allergen components in a single tube and no requirement for in vitro basophil activation. These findings endorse a single, multiplex CytoBas assay for accurate and component-resolved diagnosis of aeroallergen sensitization in patients with allergic asthma and/or rhinitis.

Non-IgE-Mediated Immediate Drug-Induced Hypersensitivity Reactions

Immediate drug-induced hypersensitivity reactions (IDHSRs) have conventionally been attributed to an immunoglobulin E (IgE)-mediated mechanism. Nevertheless, it has now been acknowledged that IDHSRs can also occur independently of IgE involvement. Non-IgE-mediated IDHSRs encompass the activation of effector cells, both mast cell-dependent and -independent and the initiation of inflammatory pathways through immunogenic and nonimmunogenic mechanisms. The IDHSRs involve inflammatory mediators beyond histamine, including the platelet-activating factor, which activates multiple cell types, including smooth muscle, endothelium, and MC, and evidence supports its importance in IgE-mediated reactions in humans. Clinically, distinguishing IgE from non-IgE mechanisms is crucial for future treatment strategies, including drug(s) restriction, readministration approaches, and pretreatment considerations. However, this presents significant challenges because certain drugs can trigger both mechanisms, and their presentations can appear similarly, ranging from mild to life-threatening symptoms. Thus, history alone is often inadequate for differentiation, and skin tests lack a standardized approach. Moreover, drug-specific IgE immunoassays have favorable specificity but low sensitivity, and the usefulness of the basophil activation test remains debatable. Lastly, no biomarker reliably differentiates between both mechanisms. Whereas non-IgE-mediated mechanisms likely predominate in IDHSRs, reclassifying most drug-related IDHSRs as non-IgE-mediated, with suggested prevention through dose administration adjustments, is premature and risky. Therefore, continued research and validated diagnostic tests are crucial to improving our capacity to distinguish between these mechanisms, ultimately enhancing patient care.

Basophil activation test in the food allergy clinic: its current use and future applications

INTRODUCTION

The basophil activation test (BAT) has shown evidence of high sensitivity and high specificity to support the diagnosis of IgE-mediated allergy. It is a functional test that uses live cells analyzed by flow cytometry and thus needs to be performed within 24h of blood collection. BAT has shown to be reproducible and reliable when tested in a clinical diagnostic laboratory with standardized protocols and flow cytometry settings.

AREAS COVERED

In this review, we summarize the evidence to support clinical use of BAT and the next steps required for clinical implementation for an improve clinical care for patients with suspected IgE-mediated food allergy.

EXPERT OPINION

BAT has recently been included in Clinical Guidelines of Food Allergy Diagnosis and its implementation in clinical practice depends largely on availability. Proposed clinical applications of the BAT include: distinction between food allergy and asymptomatic IgE sensitization; determination of food allergic status to peanut, tree nuts and seeds in polysensitized children; evaluation of tolerance to baked egg and baked milk in egg and milk allergic children; identification of patients at high-risk of severe allergic reactions; monitoring for spontaneous resolution of food allergy; confirmation of eligibility for specific treatments of food allergy; prediction and monitoring of response to immunomodulatory treatments.

Preventive allergen immunotherapy with inhalant allergens in children

The efficacy and safety of preventive allergen immunotherapy (pAIT) in children are currently under investigation. Here, we provide an overview of pAIT with respiratory allergens concerning the prevention of new sensitizations, allergic disease onset and progression as well as further immunomodulatory effects. Three databases were searched for clinical pAIT studies in children. Selected publications were reviewed for preventive outcomes according to prevention level (primary, secondary, and tertiary), allergen type, administration route, dose, and treatment duration. The primary prevention approach appears safe but showed no allergen-specific effect on new sensitizations. Secondary prevention seems feasible and may induce regulatory T cell-mediated immunotolerance. The number of studies at these prevention levels is limited. Tertiary prevention with grass and/or tree pollen-based pAIT has shown efficacy in preventing disease progression from allergic rhinitis/conjunctivitis to asthma. Data on tertiary pAIT with house dust mites and other allergen types are inconclusive. Subcutaneous and sublingual routes appear similarly effective, but head-to-head comparative paediatric studies are scarce. Additionally, there are fewer placebo-controlled studies. Nevertheless, immunomodulatory outcomes of pAIT are encouraging. Currently, limited but favourably suggestive evidence is available for preventing respiratory allergic diseases in children by pAIT. Primary and secondary prevention have potential and warrant further investigation through well-designed studies.

Promising New Diagnostic and Treatment Modalities for Allergic Rhinitis: What's Coming Next?

Novel diagnostic tests may help diagnose patients with local allergic rhinitis (AR) when systemic testing is negative or inconclusive. Surgical approaches including septoplasty, inferior turbinate reduction, nasal swell body reduction, and posterior nasal nerve ablation may improve symptoms in patients whose symptoms are refractory to medical therapy, though high-quality evidence is lacking in the AR population. Intralymphatic and epicutaneous immunotherapy have the potential to improve adherence to allergen immunotherapy, though comparisons with current gold standard treatments are lacking and studies reporting long-term outcomes are needed. Immunomodulatory agents in combination with subcutaneous immunotherapy (SCIT) may improve tolerance of SCIT but reports to date do not demonstrate a clear benefit in symptom alleviation. Future work in these areas may support these options as beneficial for testing and treatment of AR.

Specific IgE and Basophil Activation Test by Microarray: A Promising Tool for Diagnosis of Platinum Compound Hypersensitivity Reactions

Drug hypersensitivity reactions (DHRs) to platinum-based compounds (PCs) are on the rise, and their personalized and safe management is essential to enable first-line treatment for these cancer patients. This study aimed to evaluate the usefulness of the basophil activation test by flow cytometry (BAT-FC) and the newly developed sIgE-microarray and BAT-microarray in diagnosing IgE-mediated hypersensitivity reactions to PCs. A total of 24 patients with DHRs to PCs (20 oxaliplatin and four carboplatin) were evaluated: thirteen patients were diagnosed as allergic with positive skin tests (STs) or drug provocation tests (DPTs), six patients were diagnosed as non-allergic with negative STs and DPTs, and five patients were classified as suspected allergic because DPTs could not be performed. In addition, four carboplatin-tolerant patients were included as controls. The BAT-FC was positive in 2 of 13 allergic patients, with a sensitivity of 15.4% and specificity of 100%. However, the sIgE- and BAT-microarray were positive in 11 of 13 DHR patients, giving a sensitivity of over 84.6% and a specificity of 90%. Except for one patient, all samples from the non-allergic and control groups were negative for sIgE- and BAT-microarray. Our experience indicated that the sIgE- and BAT-microarray could be helpful in the endophenotyping of IgE-mediated hypersensitivity reactions to PCs and may provide an advance in decision making for drug provocation testing.

Detection of Sensitization Profiles with Cellular In Vitro Tests in Wheat Allergy Dependent on Augmentation Factors (WALDA)

Wheat allergy dependent on augmentation factors (WALDA) is the most common gluten allergy in adults. IgE-mediated sensitizations are directed towards ω5-gliadin but also to other wheat allergens. The value of the different in vitro cellular tests, namely the basophil activation test (BAT) and the active (aBHRA) and passive basophil histamine-release assays (pBHRA), in the detection of sensitization profiles beyond ω5-gliadin has not been compared. Therefore, 13 patients with challenge-confirmed, ω5-gliadin-positive WALDA and 11 healthy controls were enrolled. Specific IgE (sIgE), skin prick tests, BATs, aBHRA, and pBHRA were performed with allergen test solutions derived from wheat and other cereals, and results were analyzed and compared. This study reveals a distinct and highly individual reactivity of ω5-gliadin-positive WALDA patients to a range of wheat allergens beyond ω5-gliadin in cellular in vitro tests and SPT. In the BAT, for all tested allergens (gluten, high-molecular-weight glutenin subunits, α-amylase/trypsin inhibitors (ATIs), alcohol-free wheat beer, hydrolyzed wheat proteins (HWPs), rye gluten and secalins), basophil activation in patients was significantly higher than in controls (p = 0.004-p < 0.001). Similarly, significant histamine release was detected in the aBHRA for all test substances, exceeding the cut-off of 10 ng/mL in all tested allergens in 50% of patients. The dependency of tests on sIgE levels against ω5-gliadin differed; in the pBHRA, histamine release to any test substances could only be detected in patients with sIgE against ω5-gliadin ≥ 7.7 kU/L, whereas aBHRA also showed high reactivity in less sensitized patients. In most patients, reactivity to HWPs, ATIs, and rye allergens was observed. Additionally, alcohol-free wheat beer was first described as a promising test substance in ω5-gliadin-positive WALDA. Thus, BAT and aBHRA are valuable tools for the identification of sensitization profiles in WALDA.

Flow-based basophil activation test in immediate drug hypersensitivity. An EAACI task force position paper

Diagnosing immediate drug hypersensitivity reactions (IDHRs) can pose a significant challenge and there is an urgent need for safe and reliable tests. Evidence has emerged that the basophil activation test (BAT), an in vitro assay that mirrors the in vivo response, can be a complementary test for many drugs. In this position paper, members of Task Force (TF) "Basophil activation test in the evaluation of Drug Hypersensitivity Reactions" from the European Academy of Allergy and Clinical Immunology (EAACI) present the data from a survey about the use and utility of BAT in IDHRs in Europe. The survey results indicate that there is a great interest for using BAT especially for diagnosing IDHRs. However, there are still main needs, mainly in the standardization of the protocols. Subsequently consensus-based recommendations were formulated for: (i) Technical aspects of BAT in IDHRs including type of sample, management of drugs, flow cytometry protocols, interpretation of the results; and (ii) Drug-specific aspects that should be taken into account when performing BAT in relation to betalactams, neuromuscular blocking agents, fluoroquinolones, chlorhexidine, opioids, radio contrast media, chemotherapeutics, biological agents, nonsteroidal anti-inflammatory drugs, COVID vaccine, and excipients. Moreover, aspects in the evaluation of pediatric population have also been considered. All this indicates that BAT offers the clinician and laboratory a complementary tool for a safe diagnostic for IDHRs, although its place in the diagnostic algorithm depends on the drug class and patient population (phenotype, geography, and age). The standardization of BAT is important for generalizing this method beyond the individual laboratory.

A comprehensive review on mango allergy: Clinical relevance, causative allergens, cross-reactivity, influence of processing techniques, and management strategies

Mangoes (Mangifera indica) are widely prized for their abundant nutritional content and variety of beneficial bioactive compounds and are popularly utilized in various foods, pharmaceuticals, and cosmetics industries. However, it is important to note that certain proteins present in mango can trigger various allergic reactions, ranging from mild oral allergy syndrome to severe life-threatening anaphylaxis. The immunoglobulin E-mediated hypersensitivity of mango is mainly associated with three major allergenic proteins: Man i 1 (class IV chitinase), Man i 2 (pathogenesis-related-10 protein; Bet v 1-related protein), and Man i 4 (profilin). Food processing techniques can significantly affect the structure of mango allergens, reducing their potential to cause allergies. However, it is worth mentioning that complete elimination of mango allergen immunoreactivity has not been achieved. The protection of individuals sensitized to mango should be carefully managed through an avoidance diet, immediate medical care, and long-term oral immunotherapy. This review covers various aspects related to mango allergy, including prevalence, pathogenesis, symptoms, and diagnosis. Furthermore, the characterization of mango allergens and their potential cross-reactivity with other fruits, vegetables, plant pollen, and seeds were discussed. The review also highlights the effects of food processing on mango and emphasizes the available strategies for managing mango allergy.

Performance Characteristics of Basophil Activation Tests for Diagnosing Penicillin Allergy: A Meta-Analysis

BACKGROUND

Approximately 10% of the global population identify themselves as penicillin allergic, yet 90% are not truly allergic and could safely tolerate penicillin. There is no simple way to identify these people. Current in vitro diagnostics include specific immunoglobulin E (with a sensitivity of 19% and specificity of 97%) and a basophil activation test (BAT) with undefined sensitivity and specificity.

OBJECTIVE

To define the sensitivity and specificity of BAT in the diagnosis of penicillin allergy METHODS: We searched PubMed and EMBASE from inception to April 2, 2023, for original studies evaluating the performance characteristics of BAT for penicillin allergy in adults. Study selection, data extraction, risk of bias, assessment with QUADAS-2 tool, certainty assessment with Grading of Recommendations, Assessment, Development, and Evaluation (GRADE) methodology were performed independently, in duplicate. Meta-analysis was performed using Reitsma methodology.

RESULTS

Twenty-two studies fulfilled the inclusion criteria. Twelve used the same positive threshold giving a summary point sensitivity 51% (95% confidence interval [95% CI]46%-56%) and specificity 89% (95% CI 85%-93%). Significant risk of bias was identified owing to patient selection. GRADE certainty of evidence rated sensitivity very low due to imprecision and specificity as low. There was great heterogeneity in methods used. Use of 1,000 basophils per test did not improve performance above 500 basophils.

CONCLUSIONS

BAT sensitivity is highly variable across studies and remains too low to be considered as a routine element of clinical practice. BAT specificity is not as good as specific immunoglobulin E in penicillin allergy diagnosis. Significant further work is required in this field before clinical application of BAT in routine practice.

Allergic to bureaucracy? Regulatory allergenicity assessments of novel food: Motivations, challenges, compromises, and possibilities

New sources of proteins are essential to meet the demands of the growing world population and evolving food trends. Assessing the allergenicity of proteins in novel food (NF) poses a significant food safety regulatory challenge. The Codex Alimentarius Commission presented an allergenicity assessment protocol for genetically modified (GM) foods, which can also be adapted for NF. Since no single laboratory test can adequately predict the allergenic potential of NF, the protocol follows a weight-of-evidence approach, evaluated by experts, as part of a risk management process. Regulatory bodies worldwide have adopted this safety protocol, which, among other things, promotes global harmonization. This review unravels the reliability and various motivations, terms, concepts, and approaches of allergenicity assessments, aiming to enhance understanding among manufacturers and the public. Health Canada, Food Safety Commission JAPAN, and Food Standards Australia New Zealand were surveyed, focusing on the European Food Safety Authority and the US Food Safety Administration for examples of scientific opinions regarding allergenicity assessments for novel and GM foods, from 2019 to 2023. According to our findings, current regulatory allergenicity assessments for NF approval primarily rely on literature reviews. Only a few of the NF assessments proactively presented additional tests. We recommend conducting bioinformatic analyses on NF when a panel of experts deems that there is insufficient prior scientific research.

Whole blood stimulation as a tool for studying the human immune system

The human immune system is best accessible via tissues and organs not requiring major surgical intervention, such as blood. In many circumstances, circulating immune cells correlate with an individual's health state and give insight into physiological and pathophysiological processes. Stimulating whole blood ex vivo is a powerful tool to investigate immune responses. In the context of clinical research, the applications of whole blood stimulation include host immunity, disease characterization, diagnosis, treatment, and drug development. Here, we summarize different setups and readouts of whole blood assays and discuss applications for preclinical research and clinical practice. Finally, we propose combining whole blood stimulation with high-throughput technologies, such as single-cell RNA-sequencing, to comprehensively analyze the human immune system for the identification of biomarkers, therapeutic interventions as well as companion diagnostics.

Combining avidin with CD63 improves basophil activation test accuracy in classifying peanut allergy

BACKGROUND

Conventional basophil activation tests (BATs) measure basophil activation by the increased expression of CD63. Previously, fluorophore-labeled avidin, a positively-charged molecule, was found to bind to activated basophils, which tend to expose negatively charged granule constituents during degranulation. This study further compares avidin versus CD63 as basophil activation biomarkers in classifying peanut allergy.

METHODS

Seventy subjects with either a peanut allergy (N = 47), a food allergy other than peanut (N = 6), or no food allergy (N = 17) were evaluated. We conducted BATs in response to seven peanut extract (PE) concentrations (0.01-10,000 ng/mL) and four control conditions (no stimulant, anti-IgE, fMLP (N-formylmethionine-leucyl-phenylalanine), and anti-FcεRI). We measured avidin binding and CD63 expression on basophils with flow cytometry. We evaluated logistic regression and XGBoost models for peanut allergy classification and feature identification.

RESULTS

Avidin binding was correlated with CD63 expression. Both markers discriminated between subjects with and without a peanut allergy. Although small by percentage, an avidin+ /CD63- cell subset was found in all allergic subjects tested, indicating that the combination of avidin and CD63 could allow a more comprehensive identification of activated basophils. Indeed, we obtained the best classification accuracy (97.8% sensitivity, 96.7% specificity) by combining avidin and CD63 across seven PE doses. Similar accuracy was obtained by combining PE dose of 10,000 ng/mL for avidin and PE doses of 10 and 100 ng/mL for CD63.

CONCLUSIONS

Avidin and CD63 are reliable BAT activation markers associated with degranulation. Their combination enhances the identification of activated basophils and improves the classification accuracy of peanut allergy.

Mass Cytometry in Food Allergy Research

Mechanisms underlying food allergy are not well understood. Mass cytometry is a technique that allows the multiple analysis of cell surface markers and intracellular proteins by using the spectrum of rare metal isotopes of different atomic masses without channel overlap. Bioinformatic approaches are implemented to combine and reduce the information of more than 60 parameters to define immune cell subpopulations. To date, mass cytometry has revealed a great heterogeneity in human response to food antigens and that subpopulations of basophils and mononuclear cells might be mechanistically implicated in food allergy. This chapter reviews some fundamentals of mass cytometry and the contributions of this technique in elucidating the immune basis of food allergy, oral tolerance, food desensitization, phenotypes, and the cellular events occurring upon allergen-specific immunotherapy.

A Modified Basophil Activation Test for the Clinical Management of Immediate Hypersensitivity Reactions to Paclitaxel: A Proof-of-Concept Study

Immediate hypersensitivity reactions (iHSRs) to taxanes are observed in 6% and 4% of gynecologic and breast cancer patients, respectively. Drug desensitization is the only option, as no comparable alternative therapy is available. Surfactants in the taxane formulation have been implicated in the immunopathogenesis of iHSRs, although sporadic skin test (ST) positivity and iHSRs to nab-paclitaxel have suggested the involvement of the taxane moiety and/or IgE-mediated pathomechanisms. In vitro diagnostic tests might offer insights into mechanisms underlying iHSRs to taxanes. The aim of the present study was to address this unmet need by developing a novel basophil activation test (BAT). The study included patients (n = 31) undergoing paclitaxel/carboplatin therapy. Seventeen patients presented with iHSRs to paclitaxel (iHSR-Taxpos), and eleven were tolerant (iHSR-Taxneg). Fourteen patients presented with iHSRs to carboplatin (iHSR-Plpos), and fourteen were tolerant (iHSR-Plneg). The BAT median stimulation index (SI) values were 1.563 (range, 0.02-4.11; n = 11) and -0.28 (range -4.88-0.07, n = 11) in iHSR-Taxpos and iHSR-Taxneg, respectively. The BAT median SI values were 4.45 (range, 0.1-26.7; n = 14) and 0 (range, -0.51-1.65; n = 12) in iHSR-Plpos and iHSR-Plneg, respectively. SI levels were not associated with iHSR severity grading. Comparing BAT results in iHSR-Taxpos and iHSR-Taxneg showed the area under the receiver operator characteristic (ROC) curve to be 0.9752 (p = 0.0002). The cutoff calculated by the maximized likelihood ratio identified 90.91% of iHSR-Taxpos patients and 90.91% of iHSR-Taxneg patients. Comparing BAT results for iHSR-Plpos and iHSR-Plneg showed the area under the ROC curve to be 0.9286 (p = 0.0002). The cutoff calculated by the maximized likelihood ratio identified 78.57% of iHSR-Plpos patients and 91.67% of iHSR-Plneg patients. Most iHSR-Taxpos patients for which ST was available (10/11) scored ST-negative and BAT-positive, whereas most iHSR-Plpos patients for which ST was available (14/14) scored both BAT- and ST-positive. This suggested the intervention of non-IgE-mediated mechanisms in iHSR-Taxpos patients. Consistent with this view, an in silico molecular docking analysis predicted the high affinity of paclitaxel to the degranulation-competent MRGPRX2 receptor. This hypothesis warrants further in vitro investigations. In conclusion, the present study provides preliminary proof-of-concept evidence that this novel BAT has potential utility in understanding mechanisms underlying iHSRs to taxanes.

Autoreactive IgE: Pathogenic role and therapeutic target in autoimmune diseases

Autoimmunity is the break of tolerance to self-antigens that leads to organ-specific or systemic diseases often characterized by the presence of pathogenic autoreactive antibodies (AAb) produced by plasmablast and/or plasma cells. AAb are prevalent in the general population and not systematically associated with clinical symptoms. In contrast, in some individuals, these AAb are pathogenic and drive the development of signs and symptoms of antibody-mediated autoimmune diseases (AbAID). AAb production, isotype profiles, and glycosylations are promoted by pro-inflammatory triggers linked to genetic, environmental, and hormonal parameters. Recent evidence supports a role for pathogenic AAb of the IgE isotype in a number of AbAID. Autoreactive IgE can drive the activation of mast cells, basophils, and other types of FcεRI-bearing cells and may play a role in promoting autoantibody production and other pro-inflammatory pathways. In this review, we discuss the current knowledge on the pathogenicity of autoreactive IgE in AbAID and their status as therapeutic targets. We also highlight unresolved issues including the need for assays that reproducibly quantify IgE AAbs, to validate their diagnostic and prognostic value, and to further study their pathophysiological contributions to AbAID.

Food challenges: Patient selection, predictors, component testing, and decision points

Background

Oral food challenges are commonly used when there is uncertainty based on a clinical history as to whether a food allergy exists and to assess whether a food allergy has been outgrown.

Methods

A narrative review was performed, synthesizing available evidence in the literature.

Results

Because food challenges are generally multi-hour procedures that carry the risk for potentially severe allergic reactions, careful patient selection is important. Allergy tests can provide additional supportive information to guide decision-making but do not have sufficient diagnostic accuracy to replace food challenges in most circumstances.

Conclusion

Clinical history provides important clues with regard to the likelihood that a reaction may occur and should be combined with patient and family preferences and allergy test results when making decisions about pursuing food challenges.

Sensitivity of a Hymenoptera serological immunoglobulin (Ig)E assay for the diagnosis of venom hypersensitivity in dogs

BACKGROUND

Hymenoptera envenomation with honey bee (Apis mellifera) and paper wasp (Polistes spp.) may cause life-threatening anaphylaxis in dogs. In human patients, clinical history, intradermal testing (IDT) and measurement of allergen-specific serological immunoglobulin (Ig)E (sIgE) are used to support a diagnosis of Hymenoptera venom hypersensitivity. The utility of venom allergen-specific sIgE has not yet been evaluated for this purpose in dogs.

OBJECTIVES

The objective of the study was to investigate the sensitivity (sn), specificity (sp) and positive predictive value (PPV) of honey bee and paper wasp serological titres using a commercially available sIgE assay [VARL (Veterinary Allergen Reference Laboratory) Liquid Gold] against clinical history for a diagnosis of Hymenoptera hypersensitivity in dogs.

MATERIALS AND METHODS

Honeybee and paper wasp IgE serum titres were measured in 15 client-owned dogs with a diagnosis of Hymenoptera venom hypersensitivity based on a history of anaphylaxis, owner observation of Hymenoptera, and positive IDT to bee and/or wasp; and in 10 client-owned dogs with no known history of anaphylaxis or Hymenoptera exposure and a negative IDT to bee and wasp.

RESULTS

Analysis of receiver operating characteristic (ROC) curves demonstrate that a VARL score cut-off of one of six for honeybee yields Sn, Sp and PPV of 40%, 60% and 60%, respectively, and two of six for wasp yields Sn, Sp and PPV of 25%, 78% and 60%, respectively.

CONCLUSIONS AND CLINICAL RELEVANCE

Owing to the poor sensitivity and PPV of sIgE assays for both bee and wasp hypersensitivity in dogs with known envenomation and anaphylaxis, the use of sIgE cannot be recommended as a tool for venom identification.

Real-Life Utility of Basophil Activation Test in the Diagnosis of Immediate Hypersensitivity Drug Reactions

INTRODUCTION

The basophil activation test (BAT) is a flow cytometry laboratory technique that assesses the level of activation indicators expressed on the surface of basophils. We conducted a real-life study in a prospective cohort of patients with reported drug hypersensitivity reactions to determine the true relevance of BAT as a diagnostic tool for assessing immediate hypersensitivity reactions to medicines.

METHODS

We prospectively assessed individuals with clinical suspicion of immediate hypersensitivity reactions to drugs over a 2-year period. The allergological evaluation was carried out in accordance with European Academy of Allergy and Clinical Immunology (EAACI) guidance. All patients underwent BAT using the activation marker CD63.

RESULTS

In total 13 patients with 54 reported immediate drug hypersensitivity reactions to medications were included in this study. Twelve were female (92.3%) and one was male (7.70%). The mean ± SD age of the patients was 47.31 ± 19.94 years. Antibiotics were tested in 35.2% (19/54) of patients, corticosteroids in 24.1% (13/54), iodinated contrast medium in 14.8% (8/54), and NSAIDs in 5.6% (3/54). There was no correlation between the BAT results and the age of patients, gender, type of medication, or time interval between the allergic reaction and BAT procedure. The sensitivity of BAT 5% CD63+ basophils to drugs was 97.6%, specificity was 96% for drug allergies, positive predictive value (PPV) was 94.3%, and negative predictive value (NPV) was 95.2%.

CONCLUSIONS

The sensitivity of BAT for drug allergies is limited, but it can nevertheless be very helpful before contemplating provocation testing in cases of life-threatening drug allergies where patients cannot be rechallenged or in cases of medications for which no other tests are available or their results are ambiguous.

A novel test for type-I allergy based on crosslink formation of immunoglobulin-E receptors by allergen-specific immunoglobulin-E antibodies and an allergen

Detection of allergen-specific immunoglobulin E (IgE) antibodies (Abs) in serum would allow for screening of the causative allergen in patients with type-I allergy. In this study, we developed a new assay method to detect allergen-specific IgE Abs, which involved crosslinking the plural FcεRIα molecules with an allergen and detection using an amplified luminescence proximity homogeneous assay (AlphaCL). First, the allergen concentration, bead concentrations, and incubation time were optimized for the detection of anti-2,4-dinitrophenyl (DNP) IgE Abs in buffer. Under optimal conditions, AlphaCL was able to detect DNP-specific IgE Abs in simulated human serum at levels comparable to those in serum from type-I allergic patients. When AlphaCL was used to detect anti-DNP IgE Abs, no signal counts were obtained with the monovalent allergen 2,4-dinitrophenylated poly-γ-glutamic acid, whereas high signal counts were obtained with the multivalent allergen DNP-BSA. This confirmed that AlphaCL could specifically detect allergen-specific IgE Abs with the ability to crosslink a multivalent allergen. In summary, we have established a new assay model using AlphaCL to detect allergen-specific IgE Abs with FcεRIα crosslinking ability in human serum. This simple and practical assay model may be applied as a new diagnostic tool for patients with type-I allergy.

Delayed Nonimmune Anaphylaxis Caused by Ropivacaine for Preoperative Nerve Blocks: A Case Report

Ropivacaine is an amide local anesthetic with rare reports of anaphylaxis. To our knowledge, this is the first report of delayed nonimmune anaphylaxis induced by ropivacaine. A 70-year-old man underwent general anesthesia with a nerve block for a total knee arthroplasty. The patient developed symptoms of anaphylaxis 3.5 hours after receiving ropivacaine for femoral and tibial nerve blocks. A basophil activation test (BAT) revealed ropivacaine as the causative agent. Notably, anaphylaxis can be caused by medications even hours after their administration, and all administered drugs should be suspected of potentially causing anaphylaxis.

Targeting Lewis X oligosaccharide-modified liposomes encapsulated with house dust mite allergen Der f 2 to dendritic cells inhibits Th2 immune response

Allergen-specific immunotherapy (AIT) is the only curative treatment for allergic diseases. However, the long desensitization phase and potentially dangerous allergic side effects limit its broad application. Therefore, safer and more effective vaccines are required. Targeting dendritic cells (DCs) with novel allergen conjugates is a promising strategy for AIT. In this study, a novel vaccine with a DC-targeting effect for AIT was constructed. Liposomes were used as vehicles, and a targeted nanovaccine (Lex-lip-Der f 2) was constructed by loading the recombinant group 2 allergen of Dermatophagoides farinae (Der f 2) and conjugating with the DC-SIGN ligand Lewis X. The effect of the vaccine on DCs and T cell responses and the safety of the vaccine were investigated in vitro. The results showed that the Lex-lip-Der f 2 vaccine was spherical, with size of approximately 128 nm. The protein-loading capacity of the vaccine was 0.106 ± 0.001 mg per mg liposome and protein was gradually released from the liposomes during the first 12 h. Lex-lip-Der f 2 was taken up more efficiently by DCs than non-targeted liposomes or free Der f 2. Besides, Lex-lip-Der f 2 significantly inhibited the release of IL-4, IL-6, and TNF-a from DCs. Accordingly, Der f 2-lip loaded DCs significantly decreased IL-4 levels in autologous naïve CD4+T cells. Moreover, Lex-lip-Der f 2-treated basophils showed lower activation levels. These results suggest that DC-SIGN targeting mediated by Lewis X could inhibit the Th2 cell response and improve vaccine safety, and may be a novel vaccination strategy.

Unique allergen-specific human IgE monoclonal antibodies derived from patients with allergic disease

Introduction

Allergic reactions are mediated by human IgE antibodies that bind to and cross-link allergen molecules. The sites on allergens that are recognized by IgE antibodies have been difficult to investigate because of the paucity of IgE antibodies in a human serum. Here, we report the production of unique human IgE monoclonal antibodies to major inhaled allergens and food allergens that can be produced at scale in perpetuity.

Materials and methods

The IgE antibodies were derived from peripheral blood mononuclear cells of symptomatic allergic patients, mostly children aged 3-18 years, using hybridoma fusion technology. Total IgE and allergen-specific IgE was measured by ImmunoCAP. Their specificity was confirmed through ELISA and immunoblotting. Allergenic potency measurements were determined by ImmunoCAP inhibition. Biological activity was determined in vitro by comparing β-hexosaminidase release from a humanized rat basophilic cell line.

Results

Human IgE monoclonal antibodies (n = 33) were derived from 17 allergic patients with symptoms of allergic rhinitis, asthma, atopic dermatitis, food allergy, eosinophilic esophagitis, or red meat allergy. The antibodies were specific for five inhaled allergens, nine food allergens, and alpha-gal and had high levels of IgE (53,450-1,702,500 kU/L) with ratios of specific IgE to total IgE ranging from <0.01 to 1.39. Sigmoidal allergen binding curves were obtained through ELISA, with low limits of detection (<1 kU/L). Allergen specificity was confirmed through immunoblotting. Pairs of IgE monoclonal antibodies to Ara h 6 were identified that cross-linked after allergen stimulation and induced release of significant levels of β-hexosaminidase (35%-80%) from a humanized rat basophilic cell line.

Conclusions

Human IgE monoclonal antibodies are unique antibody molecules with potential applications in allergy diagnosis, allergen standardization, and identification of allergenic epitopes for the development of allergy therapeutics. The IgE antibody probes will enable the unequivocal localization and validation of allergenic epitopes.

An outbreak of anaphylactic transfusion reactions to group B plasma and platelets and its possible relationship to Alpha-Gal syndrome

BACKGROUND

Alpha-gal syndrome (AGS) is a potentially life-threatening acquired meat allergy associated with tick bites. The allergen Galactose-α-1,3-Galactose is antigenically similar to the B blood group antigen. B blood group status offers some protection against development of the allergy. Although not preferred practice, transfusion of plasma and platelets from group B donors is believed to be safe for group O recipients.

STUDY DESIGN AND METHODS

Anaphylactic transfusion reactions were reported for three patients in two Washington DC hospitals from Nov 2022 to February 2023. A chart review was performed for all three patients. Patients or family members were interviewed, and IgE levels to alpha-gal were measured in two of the three patients.

RESULTS

One reaction was acutely fatal. All reactions were to blood group B Plasma or Platelets in blood group O recipients. One patient had two prior anaphylactic reactions to group O RBCs and group B Plasma in a previous admission. All patients came from southern Maryland where AGS is an emerging problem. Two patients had histories of tick bites, previously unexplained gastrointestinal complaints, and abnormal elevated levels of IgE to alpha gal. Two patients had cat allergies.

DISCUSSION

AGS is an emerging problem which may have implications for blood transfusion practice. Avoidance of blood group B antigen containing components may be prudent in non-blood group B patients with established AGS. Investigation for AGS should be considered in the evaluation of anaphylactic transfusion reactions.

Promises and Remaining Challenges for Further Integration of Basophil Activation Test in Allergy-Related Research and Clinical Practice

More than 20 years after having been initially proposed, the relevance and usefulness of basophil activation test (BAT) for the field of allergy research and testing were demonstrated on many occasions. Leveraging the fully open format of a flexible, whole blood-based functional assay, BAT has been shown to be equally important for fundamental research, clinical research, and diagnosis. Regardless of whether the focus of a study is on the characterization of the allergenic moiety, on the patient side, or on the study of the fundamental processes involved in the allergic disease or its treatment, BAT enables the gathering of very important insights. In spite of this, its full capabilities have yet to be leveraged. Various bottlenecks, including but not limited to assay logistics, robustness, flow cytometry access, and/or expertise, have indeed been limiting its development beyond experts and long-term users. Now, various initiatives, aiming at resolving these bottlenecks, have been launched. If successful, a broader use of BAT could then be contemplated. In such a situation, its more thorough integration in clinical practice has the potential to significantly change the allergic patient's journey.

The Value of Current Laboratory Tests in Diagnosing Food, Venom, and Drug Allergies

An accurate diagnosis of IgE-mediated allergies is necessary to inform risk management for severe allergic reactions including anaphylaxis for food, venom, and drug allergies. The most widely available laboratory test for allergy is serum-specific IgE testing, which is routinely used for food allergy and insect sting allergy. Testing for specific IgE is limited by high sensitivity and low specificity, resulting in concern regarding overdiagnosis. Testing of allergen components has led to improved diagnosis for some food and venom allergens. Additional options for laboratory tests, such as epitope analysis, basophil activation, and mast cell activation, are being investigated for their potential to optimize diagnosis and provide predictors for reaction severity and treatment response. In contrast, laboratory testing for drug allergy is more limited because to date, there are no well-validated commercial assays in the United States. Furthermore, it is important to diagnose delayed reactions to medications, because these also significantly affect decision-making regarding therapeutic options for infectious disorders. Reliable tests for both immediate and delayed drug hypersensitivity are much needed, because drug allergy labels can significantly limit treatment options for patients. Research in this area is emerging.

Endotyping of IgE-Mediated Polyethylene Glycol and/or Polysorbate 80 Allergy

BACKGROUND

Polyethylene glycol (PEG) and polysorbate 80 (PS80) allergy preclude from SARS-CoV-2 vaccination. The mechanism(s) governing cross-reactivity and PEG molecular weight dependence remain unclear.

OBJECTIVES

To evaluate PEGylated lipid nanoparticle (LNP) vaccine (BNT162b2) tolerance and explore the mechanism of reactivity in PEG and/or PS80 allergic patients.

METHODS

PEG/PS80 dual- (n = 3), PEG mono- (n = 7), and PS80 mono-allergic patients (n = 2) were included. Tolerability of graded vaccine challenges was assessed. Basophil activation testing on whole blood (wb-BAT) or passively sensitized donor basophils (allo-BAT) was performed using PEG, PS80, BNT162b2, and PEGylated lipids (ALC-0159). Serum PEG-specific IgE was measured in patients (n = 10) and controls (n = 15).

RESULTS

Graded BNT162b2 challenge in dual- and PEG mono-allergic patients (n = 3/group) was well tolerated and induced anti-spike IgG seroconversion. PS80 mono-allergic patients (n = 2/2) tolerated single-dose BNT162b2 vaccination. Wb-BAT reactivity to PEG-containing antigens was observed in dual- (n = 3/3) and PEG mono- (n = 2/3), but absent in PS80 mono-allergic patients (n = 0/2). BNT162b2 elicited the highest in vitro reactivity. BNT162b2 reactivity was IgE mediated, complement independent, and inhibited in allo-BAT by preincubation with short PEG motifs, or detergent-induced LNP degradation. PEG-specific IgE was only detectable in dual-allergic (n = 3/3) and PEG mono-allergic (n = 1/6) serum.

CONCLUSION

PEG and PS80 cross-reactivity is determined by IgE recognizing short PEG motifs, whereas PS80 mono-allergy is PEG-independent. PS80 skin test positivity in PEG allergics was associated with a severe and persistent phenotype, higher serum PEG-specific IgE levels, and enhanced BAT reactivity. Spherical PEG exposure via LNP enhances BAT sensitivity through increased avidity. All PEG and/or PS80 excipient allergic patients can safely receive SARS-CoV-2 vaccines.