Lipid transfer proteins: the most frequent sensitizer in Italian subjects with food-dependent exercise-induced anaphylaxis

Urticaria in children and adolescents: An updated review of the pathogenesis and management

The present survey represents the latest data on diagnosis and management of childhood urticaria. It has been observed that urticaria occurs less often in children than adults, with symptoms rarely lasting for over 6 weeks. Triggers or aggravating factors can be found only in 21%-55% of cases. Finding autoantibodies in children does not impact a disease prognosis, unlike in adult patients, where the presence of autoantibodies is associated with a more prolonged run of the disease, a more severe prognosis and more intensive treatment methods. The incidence of food allergy equals to 8%-10% of cases. The incidence of Helicobacter Pylori infection in children is lower than that in adults and comes to 10%-18%. Medical experts recommend using the same treatment schemes for adults and children. This survey describes different urticaria management patterns suggested by experts from Europe, America, and Russia in their recent guidelines. It has been noted that unlike the guidelines from 2014, the 2018 clinical practice guidelines for the diagnosis and management of urticarial once again suggest a four-step treatment scheme with assigning omalizumab for Step 3 and cyclosporine A for Step 4 in the event of low therapeutic efficacy of the previous step or its impossibility. Leukotriene antagonists (LTRAs) are currently removed from basic management to alternative programs.

A robust method for the estimation and visualization of IgE cross-reactivity likelihood between allergens belonging to the same protein family

Among the vast number of identified protein families, allergens emanate from relatively few families which translates to only a small fraction of identified protein families. In allergy diagnostics and immunotherapy, interactions between immunoglobulin E and allergens are crucial because the formation of an allergen-antibody complex is necessary for triggering an allergic reaction. In allergic diseases, there is a phenomenon known as cross-reactivity. Cross-reactivity describes a situation where an individual has produced antibodies against a particular allergenic protein, but said antibodies fail to discriminate between the original sensitizer and other similar proteins that usually belong to the same family. To expound the concept of cross-reactivity, this study examines ten protein families that include allergens selected specifically for the analysis of cross-reactivity. The selected allergen families had at least 13 representative proteins, overall folds that differ significantly between families, and include relevant allergens with various potencies. The selected allergens were analyzed using information on sequence similarities and identities between members of the families as well as reports on clinically relevant cross-reactivities. Based on our analysis, we propose to introduce a new A-RISC index (Allergens’–Relative Identity, Similarity and Cross-reactivity) which describes homology between two allergens belonging to the same protein family and is used to predict the likelihood of cross-reactivity between them. Information on sequence similarities and identities, as well as on the values of the proposed A-RISC index is used to introduce four categories describing a risk of a cross-reactive reaction, namely: high, medium-high, medium-low and low. The proposed approach can facilitate analysis in component-resolved allergy diagnostics, generation of avoidance guidelines for allergic individuals, and help with the design of immunotherapy.

Anaphylaxis caused by lipid transfer proteins: an unpredictable clinical syndrome

INTRODUCTION

Lipid transfer proteins (LTPs) are panallergens found in many plant foods. They are a common cause of food-induced anaphylaxis (FIA) in adults living in the Mediterranean area. LTPs have also been proposed as a main cause of food-dependent exercise-induced anaphylaxis (FDEIA).

OBJECTIVES

Describe clinical characteristics and allergen sensitization profiles in patients with FIA related to LTP.

MATERIALS AND METHODS

Forty-three patients were included, aged 3-52 years with a clinical history of FIA and proven sensitization to LTP. Patients were tested with a multiple plant food and pollen panel and specific IgE to LTP allergens. LTP sensitization was assessed by in vivo (Pru p 3, LTP extract) and/or by in vitro tests (specific IgE, ImmunoCAP/ISAC^®).

RESULTS

Median age of first anaphylactic episode was 24 years (range 2-51), 44% had asthma, 74% were atopic and 42% had pollinosis (olive, mugwort, plane tree, wall pellitory and cypress). Co-sensitization to profilins was found in 22%. Overall in our center, LTP-induced anaphylaxis represents 17% of all causes of FIA. Foods implicated in anaphylactic reactions were: fresh fruits 51%, tree nuts 42%, vegetables (including peanut) 40% and seeds 14%. Seven patients had FDEIA.

CONCLUSIONS

LTPs are important allergens of FIA in Portugal. Clinical reactivity to several taxonomically unrelated plant foods may raise suspicion toward LTP sensitization. The association of LTP-induced anaphylaxis with pollinosis is relevant in our country. The unpredictable clinical expression depends on the effect of cofactors such as exercise. The management of avoidance plans can be challenging due to LTP being a widely cross-reacting allergen in plant foods.

Exercise-Induced Anaphylaxis: Literature Review and Recent Updates

PURPOSE OF REVIEW

This paper will review the pathophysiology, diagnosis, and treatment of exercise-induced anaphylaxis and food-dependent, exercise-induced anaphylaxis with an emphasis on novel studies published in the past several years.

RECENT FINDINGS

Exercise-induced anaphylaxis (EIAn) is a clinical syndrome characterized by anaphylaxis during or shortly after physical exertion. The syndrome is broadly grouped into two categories: exercise-induced anaphylaxis and food-dependent, exercise-induced anaphylaxis (FDEIAn). Recent literature indicates that FDEIAn is a primary IgE-mediated food allergy which is augmented by several cofactors. Cofactors such as exercise, NSAIDs, and alcohol increase intestinal permeability and allow increased antigen uptake, thereby causing symptoms. The pathophysiology of EIAn is still under investigation. EIAn and FDEIAn are rare clinical syndromes characterized by symptoms during or shortly after exercise. Despite recent advances in the understanding of EIAn and FDEIAn, the pathophysiology of both conditions is not fully understood.

Potential cofactors in accidental food allergic reactions are frequently present but may not influence severity and occurrence

BACKGROUND

Cofactors, such as physical exercise and alcohol intake, might be associated with the severity or occurrence of food allergic reactions.

OBJECTIVE

To gain insight into the frequency of presence of potential cofactors in accidental food allergic reactions in adults and to what extent these factors influence the severity and occurrence of allergic reactions.

METHODS

A prospective cohort study was conducted, with a 1-year follow-up in adult patients with a physician-diagnosed food allergy. Patients were required to fill in a questionnaire after every accidental allergic reactions to food over a 1-year period. The primary outcome measure was the frequency that potential cofactors were present in these allergic reactions.

RESULTS

A total of 157 patients were included, of which 46% reported a total of 153 reactions during a 1-year follow-up period. In 74% of the reactions, ≥1 potential cofactor was reported to be present: tiredness (38%), alcohol intake (16%), stress (14%), symptoms of pollinosis (16%), symptoms of asthma (9%), sickness/flu (3%), physical exercise (3%) and use of analgesics (2%). More than one potential cofactor was reported in almost half of all reactions (47%). There was no significant difference in the presence of these factors between mild, moderate and severe reactions (P = 0.522). In the total study population, 9% of the patients used medication that might act as cofactor (antacids, angiotensin receptor blockers [ARBs], beta blockers and angiotensin-converting enzyme inhibitors [ACEIs]) on a daily basis, which however did not influence the occurrence of reactions. Furthermore, 38% daily used allergy-suppressing medication.

CONCLUSIONS

Although factors suggested to be cofactors were frequently present during accidental food allergic reactions, we found no evidence for an association between the potential cofactors examined and reaction severity, in a population where most reactions were of mild to moderate severity.

Food allergy phenotypes: The key to personalized therapy

Food allergies (FAs) are of increasing public health concern and are characterized by a large spectrum of diseases. Their diversity is well known for immunologic pathways (IgE, non-IgE-mediated FAs) and natural history. Many other factors and patient characteristics are involved including type of food, exposure route, allergic comorbidities, gender, racial and ethnic backgrounds, cofactors and health conditions. Food allergen components and sensitization profiles are also involved in FA phenotypes. A new approach to chronic disorders based on the identification of phenotypes through extensive knowledge of all the complex components is also applicable to FAs and could lead towards integrative care management. Diagnostic biomarkers for FAs are emerging which also contribute to better care modalities. The aim of this article was to highlight current knowledge regarding the phenotypic diversity of FA. This review will focus on IgE-mediated FAs and how identifying phenotypes may help to better understand the pathophysiological complexity, improve diagnosis and lead to personalized treatment strategies.

ImmunoCAP® ISAC and Microtest for multiplex allergen testing in people with difficult to manage allergic disease: a systematic review and cost analysis

BACKGROUND

Allergy is a form of immune-mediated exaggerated sensitivity (hypersensitivity) to a substance that is either inhaled, swallowed, injected or comes into contact with the skin. Foreign substances that provoke allergies are called allergens. It has been claimed that multiplex allergen testing may help in diagnosing the cause of symptoms in patients with an unclear cause of allergy or who are allergic to more than one substance.

OBJECTIVES

To evaluate multiplex allergen testing [devices that can measure the presence of multiple immunoglobulin E (IgE) antibodies in a patient's blood at the same time], by assessing (1) clinical effectiveness (allergy symptoms, incidence of acute exacerbations, mortality, adverse events of testing and treatment, health-care presentations or admissions, health-related quality of life); (2) effects on treatment (diet, immunotherapy medications, other potential testing); (3) any additional diagnostic information provided by multiplex allergen testing; and (4) cost-effectiveness (cost of different assessment strategies).

METHODS

Fifteen databases were searched from 2005 to April 2015, including MEDLINE (via OvidSp), MEDLINE In-Process Citations, MEDLINE Daily Update, PubMed (National Library of Medicine), EMBASE, Cochrane Database of Systematic Reviews (CDSR), Cochrane Central Register of Controlled Trials (CENTRAL), Database of Abstracts of Reviews of Effects (DARE), Health Technology Assessment (HTA) database, Science Citation Index (SCI), Conference Proceedings Citation Index-Science (CPCI-S), BIOSIS Previews, Latin American and Caribbean Health Sciences Literature (LILACS), National Institute for Health Research (NIHR) HTA programme, and the US Food and Drug Administration (FDA); supplementary searches of conference proceedings and trials registries were performed. Review methods followed published guidance from the Cochrane Collaboration and the Centre for Reviews and Dissemination, University of York, UK. The methodological quality of included studies was assessed using appropriate published tools or a review-specific tool designed by the project team. Studies were summarised in a narrative synthesis. Owing to a lack of data on the clinical effectiveness of multiplex allergen testing, no long-term cost-effectiveness model was developed. A conceptual model structure was developed and cost analyses were performed to examine the short-term costs of various possible diagnostic pathways.

RESULTS

Fifteen studies were included in the review. The very limited available data indicated that the addition of multiplex allergen testing [ImmunoCAP(®) Immuno Solid-phase Allergen Chip (ISAC), Thermo Fisher Scientific/Phadia AB, Uppsala, Sweden] to standard diagnostic work-up can change the clinicians' views on the diagnosis, management and treatment of patients. There was some indication that the use of ImmunoCAP ISAC testing may be useful to guide decisions on the discontinuation of restrictive diets, the content of allergen-specific immunotherapy (SIT) prescriptions, and whether or not patients should receive SIT. However, none of the studies that we identified reported any information on clinical outcomes subsequent to changes in treatment or management. There was some evidence that ImmunoCAP ISAC may be useful for discriminating allergens that are structurally similar and are recognised by the same IgE antibody (cross-immunoreactive). No data were available for Microtest (Microtest Matrices Ltd, London, UK). Detailed cost analyses suggested that multiplex allergen testing would have to result in a substantial reduction of the proportions of patients receiving single IgE testing and oral food challenge tests in order to be cost-saving in the short term.

CONCLUSIONS

No recommendations for service provision can be made based on the analyses included in this report. It is suggested that a consensus-based protocol for the use of multiplex allergen testing be developed. The clinical effectiveness and cost-effectiveness of the proposed protocol should then be assessed by comparing long-term clinical and quality of life outcomes and resource use in patients managed using the protocol with those managed using a standard diagnostic pathway.

STUDY REGISTRATION

This study is registered as PROSPERO CRD42015019739.

FUNDING

This project was a Diagnostic Assessment Report commissioned by the NIHR HTA programme on behalf of the National Institute for Health and Care Excellence.

The clinical relevance of lipid transfer protein

Despite a huge number of studies, many aspects of the lipid transfer protein (LTP) syndrome, the most frequent primary food allergy in Mediterranean countries, remain unclear. Its peculiar geographical distribution, along with the extreme variability of its clinical expression, makes this type of food allergy something unique in the panorama of IgE-mediated food-induced allergic reactions. This review article tried to summarize the current knowledge about the most important aspects of LTP sensitization and allergy, along with the importance of positive and negative co-factors in the clinical expression of the syndrome as well as the issues regarding the cross-reactivity between LTPs present in botanically related and unrelated foods. Further, the possible absence of the protein from some plant foods is discussed.

Food-Dependent, Exercise-Induced Anaphylaxis: Diagnosis and Management in the Outpatient Setting

Food-dependent, exercise-induced anaphylaxis is a disorder in which anaphylaxis develops most predictably during exercise, when exercise takes place within a few hours of ingesting a specific food. IgE to that food should be demonstrable. It is the combination of the food and exercise that precipitates attacks, whereas the food and exercise are each tolerated independently. Recently, it was demonstrated that exercise is not essential for the development of symptoms, and that if enough of the culprit food is ingested, often with additional augmentation factors, such as alcohol or acetylsalicylic acid, symptoms can be induced at rest in the challenge setting. Thus, food-dependent, exercise-induced anaphylaxis appears to be more correctly characterized as a food allergy syndrome in which symptoms develop only in the presence of various augmentation factors, with exercise being the primary one. However, additional factors are not usually present when the patient exercises normally, so ongoing investigation is needed into the physiologic and cellular changes that occur during exercise to facilitate food-induced anaphylaxis.

Cofactors and comorbidities in patients with aspirin/NSAID hypersensitivity

Hypersensitivity reactions to aspirin and other NSAIDs occur in individuals genetically predisposed and exhibit different clinical manifestations, especially respiratory, cutaneous, and generalised. Five different phenotypes define distinct clinical pictures: aspirin-exacerbated respiratory disease, aspirin/NSAID cutaneous disease, NSAID-induced urticaria, angio-oedema and anaphylaxis, single NSAID reactions, and delayed reactions. They are observed more frequently in middle-aged women, and in atopic individuals. While ASA/NSAID hypersensitivity shares comorbidities with asthma, chronic rhinosinusitis, nasal polyposis, chronic urticaria and angio-oedema, ASA and other NSAIDs can also be cofactors for other clinically relevant conditions, especially food-dependent exercise-induced anaphylaxis, angio-oedema induced by angiotensin-converting enzyme inhibitors, and oral mite anaphylaxis. Awareness on these relationships is required for the correct diagnosis, classification, and treatment of affected patients.

Cross-reactive LTP sensitization in food-dependent exercise-induced urticaria/anaphylaxis: a pilot study of a component-resolved and in vitro depletion approach

Background

Challenge tests for food-dependent exercise-induced anaphylaxis (FDEIA) carry some risk and have a high rate of false negatives. Our aim was to explore the usefulness of an in vitro immunodepletion assay and an allergen microarray test in the identification of IgE-mediated cross-reactive food allergens in patients with suspected FDEIA or food-dependent exercise-induced urticaria and panallergen sensitization.

Methods

Three patients with a history of food dependent exercise induced urticaria/anaphylaxis and food panallergen sensitization in whom a food-exercise challenge was not feasible were selected: a 25-year-old man with cholinergic urticaria who experienced generalized urticaria and angioedema during a soccer match after drinking a peach-based soft drink; a 19-year-old woman with allergic rhinitis and controlled asthma who experienced anaphylactic shock while playing soccer, having eaten walnuts in the previous 90 min; and a 57-year-old man with baker’s asthma who experienced four episodes of anaphylaxis during exercise after ingesting wheat-containing food. All individuals underwent a diagnostic work-up with skin prick tests, specific IgE (sIgE) and ImmunoCAP ISAC test. For the in vitro immunodepletion procedure, patients’ serum was pre-incubated with the suspected native allergen (peach, walnut, or wheat) in solid phase (ImmunoCAP). The eluted serum, containing unbound IgE, was collected and samples were re-tested using Immunocap ISAC 112 and compared with baseline results.

Results

All individuals were sensitized to lipid transfer proteins. The first patient was sensitized to Pru p 3, Cor a 8, Jug r 3, and Ara h 9; after pre-incubation with peach there was 100% depletion of sIgE to all components. The second patient was sensitized to Pru p 3, Cor a 8, Jug r 3, and Ara h 9; immunodepletion with walnut depleted sIgE to Ara h 9 by 67%, Pru p 3 and Pla a 3 (60%), Art v 3 (75%), Jug r 3 (88%), and Cor a 8 (100%). The third patient was sensitized to Pru p 3, Jug r 3, Ara h 9, and Tri a 14; immunodepletion with wheat depleted Tri a 14 only (100%).

Conclusions

In vitro immunodepletion might be a useful diagnostic tool in food dependent exercise induced urticaria/anaphylaxis with panallergen sensitization, particularly for identifying the culprit allergen and guiding dietary elimination recommendations.

IgE cross-reactivity of peanut with walnut and soybean in children with food allergy

BACKGROUND

Peanut allergies are common and can be life-threating for sensitised individuals. Peanut allergens share significant amino acid homology with those of other legumes and tree nuts, but their cross-reactivity still remains unclear.

OBJECTIVE

We sought to determine the clinical significance of the cross-reactivity of peanut allergens with those of walnut and soybean.

METHODS

Pooled sera from eight subjects with both peanut and walnut specific IgE were investigated in an inhibition test. After the sera were incubated with either peanut or walnut protein extracts, the quantity of IgE antibodies against the peanut and walnut was measured using an immunoCAP test. Likewise, pooled sera from 18 subjects with both peanut and soybean specific IgE antibodies were incubated with either peanut or soybean protein extracts and evaluated with a peanut and soybean immunoCAP test. SDS-PAGE and immunoblotting were also performed with peanut, walnut and soybean protein extracts and relevant sera.

RESULTS

Peanut specific IgE was inhibited up to 20% and 26% by walnut and soybean protein extracts, respectively. In reverse, walnut and soybean specific IgE were inhibited up to 21% and 23% by peanut protein extracts, respectively. In the immunoblot analysis, pooled serum from the subjects with peanut specific IgE antibodies reacted with walnut protein extracts significantly.

CONCLUSION

Although the clinical significance of the cross-reactivity of peanut specific IgE with walnut and soybean protein extracts has not been established, we believe that individuals who are allergic to peanuts need to be cautious about consuming walnuts and soybeans.

Diagnosis of exercise-induced anaphylaxis: current insights

Exercise-induced anaphylaxis (EIAn) is defined as the occurrence of anaphylactic symptoms (skin, respiratory, gastrointestinal, and cardiovascular symptoms) after physical activity. In about a third of cases, cofactors, such as food intake, temperature (warm or cold), and drugs (especially nonsteroidal anti-inflammatory drugs) can be identified. When the associated cofactor is food ingestion, the correct diagnosis is food-dependent EIAn (FDEIAn). The literature describes numerous reports of FDEIAn after intake of very different foods, from vegetables and nuts to meats and seafood. One of the best-characterized types of FDEIAn is that due to ω5-gliadin of wheat, though cases of FDEIAn after wheat ingestion by sensitization to wheat lipid transfer protien (LTP) are described. Some pathophysiological mechanisms underlying EIAn have been hypothesized, such as increase/alteration in gastrointestinal permeability, alteration of tissue transglutaminase promoting IgE cross-linking, enhanced expression of cytokines, redistribution of blood during physical exercise leading to altered mast-cell degranulation, and also changes in the acid–base balance. Nevertheless, until now, none of these hypotheses has been validated. The diagnosis of EIAn and FDEIAn is achieved by means of a challenge, with physical exercise alone for EIAn, and with the assumption of the suspected food followed by physical exercise for FDEIAn; in cases of doubtful results, a double-blind placebo-controlled combined food–exercise challenge should be performed. The prevention of this particular kind of anaphylaxis is the avoidance of the specific trigger, ie, physical exercise for EIAn, the assumption of the culprit food before exercise for FDEIAn, and in general the avoidance of the recognized cofactors. Patients must be supplied with an epinephrine autoinjector, as epinephrine has been clearly recognized as the first-line intervention for anaphylaxis.

Recent advances in component resolved diagnosis in food allergy

Due to the high prevalence of food allergic diseases globally there are increasing demands in clinical practice for managing IgE-mediated conditions. During the last decade, component resolved diagnostics has been introduced into the field of clinical allergology, providing information that cannot be obtained from extract-based tests. Component resolved data facilitate more precise diagnosis of allergic diseases and identify sensitizations attributable to cross-reactivity. Furthermore it assists risk assessment in clinical practice as sensitization to some allergenic molecules is related to persistence of clinical symptoms and systemic rather than local reactions. The information may also aid the clinician in prescription of oral immunotherapy (OIT) in patients with severe symptoms, and in giving advice on food allergen avoidance or on the need to perform food challenges. The use of allergen components is rapidly evolving and increases our possibility to treat food allergic patients with a more individual approach. Using molecular allergology, we can already now better diagnose, prognose and grade the food allergy. In summary, daily routine molecular allergy diagnostics offers a number of benefits that give us a higher diagnostic precision and allow for better management of the patient.

Biomarkers for Allergen Immunotherapy: A "Panoromic" View

Biomarkers (BMKs) are biological parameters that can be measured to predict or monitor disease severity or treatment efficacy. The induction of regulatory dendritic cells (DCs) concomitantly with a downregulation of proallergic DC2s (ie, DCs supporting the differentiation of T-helper lymphocyte type 2 cells) in the blood of patients allergic to grass pollen has been correlated with the early onset of allergen immunotherapy efficacy. The combined use of omics technologies to compare biological samples from clinical responders and nonresponders is being implemented in the context of nonhypothesis-driven approaches. Such comprehensive "panoromic" strategies help identify completely novel candidate BMKs, to be subsequently validated as companion diagnostics in large-scale clinical trials.

Asymptomatic LTP sensitisation is common in plant-food allergic children from the Northeast of Spain

BACKGROUND

The sensitisation profile at molecular level in plant-food allergy is complex. Several allergens may be involved, with different potential for severe reactions. lipid transfer proteins (LTP) are considered the most relevant plant-food allergens in adults in Mediterranean countries, but less is known in children.

AIM

To describe the clinical pattern and sensitisation profile of children with plant-food allergy and LTP sensitisation from Northeast Spain.

METHODS

Children with history of immediate reaction to plant-food(s), positive skin-prick-test to the culprit plant-food(s) and specific-IgE to plant-food LTPs were analysed.

RESULTS

130 children were included. 69.2% (90/130) had reacted to ≥2 taxonomically unrelated plant-foods. Peach, walnut, hazelnut and peanut were most frequently involved. Reactions severity ranged from anaphylaxis (45.4%, 59/130) to oral symptoms only. Sensitisation to a particular plant-food LTP not always caused clinical symptoms with that plant-food; 69% (40/58) and 63% (17/27) of peach- and walnut-tolerant subjects had positive rPru p 3 and nJug r 3 specific IgE, respectively. 65.4% (85/130) of children were also sensitised to storage proteins, which was associated to anaphylaxis and nut allergy. However, 60% of patients without nuts/seeds allergy were sensitised to storage proteins. Specific-IgE levels to LTPs and/or storage proteins were not useful to predict allergy (vs. tolerance) to peach, walnut, peanut or hazelnut.

CONCLUSIONS

Sensitisation to LTP and/or storage proteins without clear clinical significance is relatively common. Prospective longitudinal studies are required to evaluate the relevance of these silent sensitisations over time. Caution is required when interpreting the results of molecular-based diagnostic tools in clinical practice.

Multiplex component-based allergen microarray in recent clinical studies

During the last decades component-resolved diagnostics either as singleplex or multiplex measurements has been introduced into the field of clinical allergology, providing important information that cannot be obtained from extract-based tests. Here we review recent studies that demonstrate clinical applications of the multiplex microarray technique in the diagnosis and risk assessment of allergic patients, and its usefulness in studies of allergic diseases. The usefulness of ImmunoCAP ISAC has been validated in a wide spectrum of allergic diseases like asthma, allergic rhinoconjunctivitis, atopic dermatitis, eosinophilic esophagitis, food allergy and anaphylaxis. ISAC provides a broad picture of a patient's sensitization profile from a single test, and provides information on specific and cross-reactive sensitizations that facilitate diagnosis, risk assessment, and disease management. Furthermore, it can reveal unexpected sensitizations which may explain anaphylaxis previously categorized as idiopathic and also display for the moment clinically non-relevant sensitizations. ISAC can facilitate a better selection of relevant allergens for immunotherapy compared with extract testing. Microarray technique can visualize the allergic march and molecular spreading in the preclinical stages of allergic diseases, and may indicate that the likelihood of developing symptomatic allergy is associated with specific profiles of sensitization to allergen components. ISAC is shown to be a useful tool in routine allergy diagnostics due to its ability to improve risk assessment, to better select relevant allergens for immunotherapy as well as detecting unknown sensitization. Multiplex component testing is especially suitable for patients with complex symptomatology.

Structure, stability, and IgE binding of the peach allergen Peamaclein (Pru p 7)

Knowledge of the structural properties of allergenic proteins is a necessary prerequisite to better understand the molecular bases of their action, and also to design targeted structural/functional modifications. Peamaclein is a recently identified 7 kDa peach allergen that has been associated with severe allergic reactions in sensitive subjects. This protein represents the first component of a new allergen family, which has no 3D structure available yet. Here, we report the first experimental data on the 3D-structure of Peamaclein. Almost 75% of the backbone resonances, including two helical stretches in the N-terminal region, and four out of six cysteine pairs have been assigned by 2D-NMR using a natural protein sample. Simulated gastrointestinal digestion experiments have highlighted that Peamaclein is even more resistant to digestion than the peach major allergen Pru p 3. Only the heat-denatured protein becomes sensitive to intestinal proteases. Similar to Pru p 3, Peamaclein keeps its native 3D-structure up to 90°C, but it becomes unfolded at temperatures of 100-120°C. Heat denaturation affects the immunological properties of both peach allergens, which lose at least partially their IgE-binding epitopes. In conclusion, the data collected in this study provide a first set of information on the molecular properties of Peamaclein. Future studies could lead to the possible use of the denatured form of this protein as a vaccine, and of the inclusion of cooked peach in the diet of subjects allergic to Peamaclein.

EAACI Molecular Allergology User's Guide

The availability of allergen molecules ('components') from several protein families has advanced our understanding of immunoglobulin E (IgE)-mediated responses and enabled 'component-resolved diagnosis' (CRD). The European Academy of Allergy and Clinical Immunology (EAACI) Molecular Allergology User's Guide (MAUG) provides comprehensive information on important allergens and describes the diagnostic options using CRD. Part A of the EAACI MAUG introduces allergen molecules, families, composition of extracts, databases, and diagnostic IgE, skin, and basophil tests. Singleplex and multiplex IgE assays with components improve both sensitivity for low-abundance allergens and analytical specificity; IgE to individual allergens can yield information on clinical risks and distinguish cross-reactivity from true primary sensitization. Part B discusses the clinical and molecular aspects of IgE-mediated allergies to foods (including nuts, seeds, legumes, fruits, vegetables, cereal grains, milk, egg, meat, fish, and shellfish), inhalants (pollen, mold spores, mites, and animal dander), and Hymenoptera venom. Diagnostic algorithms and short case histories provide useful information for the clinical workup of allergic individuals targeted for CRD. Part C covers protein families containing ubiquitous, highly cross-reactive panallergens from plant (lipid transfer proteins, polcalcins, PR-10, profilins) and animal sources (lipocalins, parvalbumins, serum albumins, tropomyosins) and explains their diagnostic and clinical utility. Part D lists 100 important allergen molecules. In conclusion, IgE-mediated reactions and allergic diseases, including allergic rhinoconjunctivitis, asthma, food reactions, and insect sting reactions, are discussed from a novel molecular perspective. The EAACI MAUG documents the rapid progression of molecular allergology from basic research to its integration into clinical practice, a quantum leap in the management of allergic patients.

Provocation tests for the diagnosis of food-dependent exercise-induced anaphylaxis

BACKGROUND

Little has been reported regarding provocation tests for the diagnosis of food-dependent exercise-induced anaphylaxis (FDEIA), especially in children and adolescents. Hence, we here aimed to examine the usefulness and safety of such tests for FDEIA.

METHODS

We retrospectively analyzed 41 patients with 184 provocation tests. The patients underwent ergometer stress tests after ingesting the suspected foods along with aspirin. When one or more allergic symptoms appeared, we judged the provocation test as positive.

RESULTS

Based on 30 positive test results (16%), we diagnosed 20 patients (49%) as FDEIA. The major causative foods were as follows: wheat alone (five patients), combination of wheat and shrimp (three patients), combination of wheat and apple (two patients), and peach alone (two patients). The symptoms appeared within 45 min after initiating exercise in 29 tests (97%). The most frequent symptoms were cutaneous symptoms, which appeared in 25 tests (83%). Of the 30 positive tests, 6 (20%) required administration of adrenaline. After discharge, the patients with negative test results had no episodes of FDEIA due to the suspected foods that they had been tested for.

CONCLUSION

Provocation tests enabled us to confirm the diagnosis of FDEIA when positive and to exclude the diagnosis when negative. However, as severe symptoms may appear, these tests should be performed in a hospital under constant supervision of a physician.

Diagnosis of Food Allergy

The prevalence of food allergies has been on the increase over the last 2 decades. Diagnosing food allergies can be complicated, as there are multiple types that have distinct clinical and immunologic features. Food allergies are broadly classified into immunoglobulin E (IgE)-mediated, non-IgE-mediated, or mixed food allergic reactions. This review focuses on the clinical manifestations of the different categories of food allergies and the different tests available to guide the clinician toward an accurate diagnosis.

Common food allergens and their IgE-binding epitopes

Food allergy is an adverse immune response to certain kinds of food. Although any food can cause allergic reactions, chicken egg, cow's milk, wheat, shellfish, fruit, and buckwheat account for 75% of food allergies in Japan. Allergen-specific immunoglobulin E (IgE) antibodies play a pivotal role in the development of food allergy. Recent advances in molecular biological techniques have enabled the efficient analysis of food allergens. As a result, many food allergens have been identified, and their molecular structure and IgE-binding epitopes have also been identified. Studies of allergens have demonstrated that IgE antibodies specific to allergen components and/or the peptide epitopes are good indicators for the identification of patients with food allergy, prediction of clinical severity and development of tolerance. In this review, we summarize our current knowledge regarding the allergens and IgE epitopes in the well-researched allergies to chicken egg, cow's milk, wheat, shrimp, and peanut.

Lipid transfer protein sensitization: reactivity profiles and clinical risk assessment in an Italian cohort

BACKGROUND

Nonspecific lipid transfer proteins (nsLTPs) represent a major cause of systemic food allergic reactions in the Mediterranean area. This study investigate hierarchical patterns and cluster relationships of IgE sensitization to different nsLTPs, and the relationship to clinical allergy in a large Italian cohort.

METHODS

A total of 568 nsLTP-positive subjects after IgE ImmunoCAP-ISAC microarray analysis with Ara h 9, Art v 3, Cor a 8, Jug r 3, Pla a 3, Pru p 3 and Tri a 14 allergens were studied. IgE inhibition experiments were carried out with mugwort and plane tree pollen extracts.

RESULTS

Eighty-two per cent of nsLTP-positive participants (94% if <6 years old) were Pru p 3(pos) , and 71% were Jug r 3(pos) . Participants who reacted to >5 nsLTPs reported a higher incidence of food-induced systemic reactions. Only Art v 3 and Pla a 3 (mugwort and plane tree nsLTPs, respectively) were associated with respiratory symptoms, and a correlation was observed between sensitization to pollen and plant food nsLTPs, particularly between Pla a 3 and tree nut/peanut nsLTPs. Co-sensitization to Par j 2 and PR-10 or profilin pan-allergens was associated with a lower prior prevalence of severe food-induced reactions. In inhibition assays, plane and mugwort pollen extracts inhibited 50-100% of IgE binding to food nsLTPs in microarrays.

CONCLUSIONS

Testing IgE reactivity to a panel of nsLTP allergens unveils important associations between nsLTP sensitization profiles and clinical presentation and allows the identification of novel cluster patterns indicating likely cross-reactivities and highlighting potential allergens for nsLTP immunotherapy.

Distinct transcriptome profiles differentiate nonsteroidal anti-inflammatory drug-dependent from nonsteroidal anti-inflammatory drug-independent food-induced anaphylaxis

BACKGROUND

Lipid transfer protein (LTP), an abundant protein in fruits, vegetables, and nuts, is a common food allergen in Mediterranean areas causing diverse allergic reactions. Approximately 40% of food-related anaphylaxis induced by LTPs requires nonsteroidal anti-inflammatory drugs (NSAIDs) as a triggering cofactor.

OBJECTIVE

We sought to better understand the determinants of NSAID-dependent and NSAID-independent LTP-induced anaphylaxis (LTP-A).

METHODS

Selection of patients was based on a proved clinical history of NSAID-dependent or NSAID-independent anaphylaxis to LTPs, positive skin prick test response to LTPs, and serum LTP IgE. Whole-transcriptome (RNA sequencing) analysis of blood cells from 14 patients with NSAID-related LTP-A (NSAID-LTP-A), 7 patients with LTP-A, and 13 healthy control subjects was performed to identify distinct gene expression signatures.

RESULTS

Expression of genes regulating gastrointestinal epithelial renewal was altered in both patient sets, particularly in those with LTP-A, who also presented with gene expression profiles characteristic of an inflammatory syndrome. These included altered B-cell pathways, increased neutrophil activation markers, and increased reactive oxygen species levels. Increased expression of the IgG receptor (CD64) in patients with LTP-A was mirrored by the presence of LTP-specific IgG1 and IgG3. Conversely, patients with NSAID-LTP-A were characterized by reduced expression of IFN-γ-regulated genes and IFN-γ levels, as well as upregulated expression of adenosine receptor 3 (ADORA3) and genes related to adenosine metabolism.

CONCLUSIONS

Gene ontology analysis suggests disturbances in gut epithelial homeostasis in both groups with LTP-A, with potential integrity breaches in patients with LTP-A that might explain their distinct inflammatory signatures. Differential regulation in patients with LTP-A and those with NSAID-LTP-A of the IFN-γ pathway, IgG receptors, and ADORA3 might provide the pathogenic basis of their distinct responses.

Anaphylaxis to food

This article provides a clinically focused review of food-induced anaphylaxis that includes epidemiology, risk factors, allergens, diagnosis, and management. Currently, there is no treatment for food allergy. Dietary avoidance and emergency preparedness are the cornerstones of management. Effective and safe therapies to reduce the risk of serious food-induced reactions are urgently needed, as are reliable biomarkers to predict severity.

The development of a standardised diet history tool to support the diagnosis of food allergy

The disparity between reported and diagnosed food allergy makes robust diagnosis imperative. The allergy-focussed history is an important starting point, but published literature on its efficacy is sparse. Using a structured approach to connect symptoms, suspected foods and dietary intake, a multi-disciplinary task force of the European Academy of Allergy and Clinical Immunology developed paediatric and adult diet history tools. Both tools are divided into stages using traffic light labelling (red, amber and green). The red stage requires the practitioner to gather relevant information on symptoms, atopic history, food triggers, foods eaten and nutritional issues. The amber stage facilitates interpretation of the responses to the red-stage questions, thus enabling the practitioner to prepare to move forward. The final green stage provides a summary template and test algorithm to support continuation down the diagnostic pathway. These tools will provide a standardised, practical approach to support food allergy diagnosis, ensuring that all relevant information is captured and interpreted in a robust manner. Future work is required to validate their use in diverse age groups, disease entities and in different countries, in order to account for differences in health care systems, food availability and dietary norms.

Exercise-induced Anaphylaxis: the Role of Cofactors

Introduction:

Anaphylaxis is a dramatic clinical emergency. It is a very severe, life-threatening generalized or systemic hypersensitivity reaction. Based on immunologic mechanism the anaphylaxis is divided in IgE, IgG, complement, or immune complexes-mediated vs non allergic anaphylaxis. There are a lot of etiologic factors of anaphylaxis, but the three principal immunologic triggers are drugs, insect stings, and foods. Regarding the clinical severity there are several proposed grading systems. The diagnosis of anaphylaxis is mainly clinical.

Discussion:

The anaphylaxis markers measured in clinical laboratories are total tryptase and histamine. There are some conditions that modulate the onset of anaphylaxis, acting as co- or augmentation factors, which significantly lower the allergen dose necessary for triggering anaphylaxis. The well-documented cofactors of anaphylaxis are physical exercise, alcohol consumption, some foods, co-administration of nonsteroidal anti-inflammatory drugs (NSAID), and concomitant infectious diseases. Development of anaphylaxis depends on the sensitization pattern, the proportion of the involved immunoglobulin classes, characteristics of the allergen, the proportion of the involved immunoglobulin classes, the avidity and affinity of immunoglobulins to bind an allergen, the route of allergen application, and, last but not least, the presence of cofactors of anaphylaxis.

Conclusion:

Anaphylaxis remains a continuous challenge for the diagnosis and treatment. The adequate management of anaphylaxis requires rapid diagnosis, implementation of primary and secondary prevention measures, and immediate administration of subcutaneous epinephrine.

A Pitfall to Avoid When Using an Allergen Microarray: The Incidental Detection of IgE to Unexpected Allergens

The introduction of new laboratory techniques to detect specific IgE antibodies against single allergen molecules rather than whole extracts represents a significant advance in allergy diagnostics. The advantages of such component-resolved diagnosis can be summarized as follows: (1) the ability to identify the truly responsible allergens in polysensitized patients, whether they be genuine (causing specific sensitization to their corresponding allergen source) or primary (the original sensitizing molecule); (2) distinguishing these allergens from simply cross-reactive components; (3) improving the appropriateness of the prescribed specific immunotherapy; and (4) identifying a risk profile for food allergens. Component-resolved diagnosis is performed using either a singleplex (1 assay per sample) platform or a multiplex (multiple assays per sample) platform. Using an immuno solid-phase allergen chip microarray that falls into the latter category--it currently tests sensitivity to 112 allergens--may lead to a pitfall: detecting IgE to unexpected allergens, such as Hymenoptera venom. In fact, testing insect venom sensitivity in individuals with no history of reactions to stings is contrary to current guidelines and presents the physician with the dilemma of how to manage this information; moreover, this may become a legal issue. Based on what is currently known about venom allergy, it remains likely that a positive sensitization test result will have no clinical significance, but the possibility of reacting to a future sting cannot be completely ruled out. Because this problem has not been previously encountered using the more common allergy tests, no indications are currently available on how to effectively manage these cases.

Component resolved diagnosis: when should it be used?

The knowledge on molecular allergy diagnosis is continuously evolving. It is now time for the clinician to integrate this knowledge and use it when needed to improve the accuracy of diagnosis and thus provide more precise therapeutic and avoidance measures. This review does not intend to comprehensively analyze all the available allergen molecules, but to provide some practical clues on use and interpretation of molecular allergy diagnosis. The potential role of component resolved diagnosis in circumstances such as the indication of allergen immunotherapy, pollen polysensitization, food allergy, latex allergy or anaphylaxis, is assessed. Interpreting the information provided by molecular allergy diagnosis needs a structured approach. It is necessary to evaluate single positivities and negativities, but also to appraise "the big picture" with perspective.

EAACI food allergy and anaphylaxis guidelines: diagnosis and management of food allergy

Food allergy can result in considerable morbidity, impact negatively on quality of life, and prove costly in terms of medical care. These guidelines have been prepared by the European Academy of Allergy and Clinical Immunology's (EAACI) Guidelines for Food Allergy and Anaphylaxis Group, building on previous EAACI position papers on adverse reaction to foods and three recent systematic reviews on the epidemiology, diagnosis, and management of food allergy, and provide evidence-based recommendations for the diagnosis and management of food allergy. While the primary audience is allergists, this document is relevant for all other healthcare professionals, including primary care physicians, and pediatric and adult specialists, dieticians, pharmacists and paramedics. Our current understanding of the manifestations of food allergy, the role of diagnostic tests, and the effective management of patients of all ages with food allergy is presented. The acute management of non-life-threatening reactions is covered in these guidelines, but for guidance on the emergency management of anaphylaxis, readers are referred to the related EAACI Anaphylaxis Guidelines.

Developments in the field of allergy in 2012 through the eyes of Clinical & Experimental Allergy

In 2012, we received 683 submissions and published 20 editorials, 38 reviews, 11 letters and 128 original articles. This represents an acceptance rate for original papers in the range of 20%. About 30% of original papers were triaged not to go out to review, either because the editors did not feel they had sufficient priority for publication or because the topic did not feel right for the readers of the journal. We place great emphasis on obtaining sufficient high-quality reviews to make our decisions on publication fair and consistent. Inevitably, however, there is a degree of luck about what gets published and which papers miss out, and we are always happy to receive an appeal on our decisions either at the triage stage or after review. This gives us the opportunity to revisit the decision and revise it or explain in more detail to the authors the basis for the decision. Once again in 2012, we were delighted by the quality of the papers submitted and the breadth and depth of research into allergic disease that it revealed. The pattern of papers submitted was similar in previous years with considerable emphasis on all aspects of asthma and rhinitis. We were particularly pleased with our special issue on severe asthma. Elucidating mechanisms using either animal models or patients has always been a major theme of the journal, and the excellent work in these areas has been summarized by Harissios Vliagoftis with a particularly interesting section on early-life events guiding the development of allergic disease, which understandably continue to be a major theme of research. Magnus Wickman summarized the papers looking at the epidemiology of allergic disease including work from birth cohorts, which are an increasingly rich source of data on risk factors for allergic disease, and two papers on the epidemiology of anaphylaxis. Giovanni Passalacqua discussed the papers in the clinical allergy section of the journal, and Adriano Mari who runs the excellent Allergome website discussed the papers looking at allergens including characterization and the relative usefulness of allergen arrays versus single extracts in diagnosis and management.

Food-dependent exercise-induced anaphylaxis with negative allergy testing

Food-dependent exercise-induced anaphylaxis (FDEIA) is a disorder where exercise following allergen ingestion triggers anaphylaxis although exercise and allergen exposure are independently tolerated. The diagnosis of FDEIA is based on a characteristic clinical history. The culprit allergen is usually confirmed through the use of skin prick testing (SPT) serum-specific IgE levels and a food-exercise challenge. We present a case of FDEIA suggested by clinical history and open food-exercise challenge with negative specific IgE levels and SPT that highlights the challenges involved in diagnosing and managing this rare disorder.

Anaphylaxis to plant-foods and pollen allergens in patients with lipid transfer protein syndrome

PURPOSE OF REVIEW

Nonspecific lipid transfer protein (LTP) is the main cause of primary food allergy in adults living in the Mediterranean area. The way allergic patients get sensitized to this protein is all but established, and the clinical expression of sensitization is extremely variable, ranging from long-lasting symptomless sensitization to severe anaphylaxis. Such variability is seemingly due to the presence/absence of a number of cofactors.

RECENT FINDINGS

The possibility that LTP sensitization occurs via the inhalation of LTP-containing pollen particles seems unlikely; in contrast, peach particles containing the protein seem able to sensitize both via the airways and the skin. Cosensitization to pollen allergens as well as to labile plant food allergens makes LTP allergy syndrome less severe. In some LTP sensitized subjects clinical food allergy occurs only in the presence of cofactors such as exercise, NSAIDs, or chronic urticaria.

SUMMARY

Lipid transfer protein allergy syndrome shows some peculiarities that are unique in the primary food allergy panorama: geographical distribution, frequent asymptomatic sensitization, frequent need for cofactors, and reduced severity when pollen allergy is present. Future studies will have to address these points as the results may have favorable effects on other, more severe, types of food allergy.

A WAO - ARIA - GA²LEN consensus document on molecular-based allergy diagnostics

Molecular-based allergy (MA) diagnostics is an approach used to map the allergen sensitization of a patient at a molecular level, using purified natural or recombinant allergenic molecules (allergen components) instead of allergen extracts. Since its introduction, MA diagnostics has increasingly entered routine care, with currently more than 130 allergenic molecules commercially available for in vitro specific IgE (sIgE) testing.

MA diagnostics allows for an increased accuracy in allergy diagnosis and prognosis and plays an important role in three key aspects of allergy diagnosis: (1) resolving genuine versus cross-reactive sensitization in poly-sensitized patients, thereby improving the understanding of triggering allergens; (2) assessing, in selected cases, the risk of severe, systemic versus mild, local reactions in food allergy, thereby reducing unnecessary anxiety for the patient and the need for food challenge testing; and (3) identifying patients and triggering allergens for specific immunotherapy (SIT).

Singleplex and multiplex measurement platforms are available for MA diagnostics. The Immuno-Solid phase Allergen Chip (ISAC) is the most comprehensive platform currently available, which involves a biochip technology to measure sIgE antibodies against more than one hundred allergenic molecules in a single assay. As the field of MA diagnostics advances, future work needs to focus on large-scale, population-based studies involving practical applications, elucidation and expansion of additional allergenic molecules, and support for appropriate test interpretation. With the rapidly expanding evidence-base for MA diagnosis, there is a need for allergists to keep abreast of the latest information. The aim of this consensus document is to provide a practical guide for the indications, determination, and interpretation of MA diagnostics for clinicians trained in allergology.

World Allergy Organization Anaphylaxis Guidelines: 2013 update of the evidence base

The World Allergy Organization (WAO) Guidelines for the assessment and management of anaphylaxis are a widely disseminated and used resource for information about anaphylaxis. They focus on patients at risk, triggers, clinical diagnosis, treatment in health care settings, self-treatment in the community, and prevention of recurrences. Their unique strengths include a global perspective informed by prior research on the global availability of essentials for anaphylaxis assessment and management and a global agenda for anaphylaxis research. Additionally, detailed colored illustrations are linked to key concepts in the text [Simons et al.: J Allergy Clin Immunol 2011;127:593.e1-e22]. The recommendations in the original WAO Anaphylaxis Guidelines for management of anaphylaxis in health care settings and community settings were based on evidence published in peer-reviewed, indexed medical journals to the end of 2010. These recommendations remain unchanged and clinically relevant. An update of the evidence base was published in 2012 [Simons et al.: Curr Opin Allergy Clin Immunol 2012;12:389-399]. In 2012 and early 2013, major advances were reported in the following areas: further characterization of patient phenotypes; development of in vitro tests (for some allergens) that help distinguish clinical risk of anaphylaxis from asymptomatic sensitization; epinephrine (adrenaline) research, including studies of a new epinephrine auto-injector for use in community settings, and randomized controlled trials of immunotherapy to prevent food-induced anaphylaxis. Despite these advances, the need for additional prospective studies, including randomized controlled trials of interventions in anaphylaxis is increasingly apparent. This 2013 Update highlights publications from 2012 and 2013 that further contribute to the evidence base for the recommendations made in the original WAO Anaphylaxis Guidelines. Ideally, it should be used in conjunction with these Guidelines and with the 2012 Guidelines Update.

Food allergy: management, diagnosis and treatment strategies

Food allergy is an increasing problem in western countries, with strict avoidance being the only available reliable treatment. However, accidental ingestion can occur and anaphylactic reactions still happen. In recent years, many efforts have been made to better understand the humoral and cellular mechanisms involved in food allergy, and to improve the strategies for diagnosis and treatment. This review focuses on IgE-mediated food hypersensitivity and provides an overview of the diagnostic strategies and treatment advances. Specific immunotherapy, including different routes of administration and allergen sources, such as natural, recombinant and T-cell epitopes, are analyzed in detail. Other treatments such as anti-IgE monoclonal antibody therapy, adjuvant therapy and Chinese herbs will also be described.