Component-resolved diagnostics demonstrates that most peanut-allergic individuals could potentially introduce tree nuts to their diet

Diagnosis and Management of Pollen Food Allergy Syndrome to Nuts

Oral allergy syndrome or pollen food allergy syndrome (PFAS) represents a common clinical conundrum when the reported trigger food is a tree nut (usually almond or hazelnut) or peanut. The PFAS may give rise to uncertainty about the potential severity of the future reactions, indications for prescribing epinephrine, and the extent of the necessary dietary avoidance. As a food allergy, secondary to cross-reactivity with airborne pollen, PFAS usually manifests toward the end of the first decade of life as contact urticaria of the oropharyngeal mucous membranes. Molecular allergology facilitates diagnosis and risk stratification by establishing the profile of sensitization. Exclusive sensitization to pathogenesis-related proteins family 10 (PR10) and profilins indicates that signs and symptoms are due to PFAS, whereas sensitization to seed storage proteins with or without sensitization to PR10 and profilins may indicate a more severe primary nut allergy phenotype. Management relies on avoidance of the specific nut trigger, advice on the likelihood of more severe local or systemic symptoms, and treatment of reactions according to the severity. Future studies are needed to better delineate the risk of systemic reactions in individuals with nut PFAS and to establish the role of food or pollen allergen immunotherapy for the prevention or moderation of this condition.

Peanut Allergy and Component-Resolved Diagnostics Possibilities-What Are the Benefits?

Peanut allergy is a widespread and potentially life-threatening condition that affects both children and adults, with a growing incidence worldwide. It is estimated to affect around 1-2% of the population in several developed countries. Component-resolved diagnostics is a modern approach to allergy diagnosis that focuses on identifying specific allergenic proteins to provide precise diagnoses and personalized treatment plans. It is a technique that enables the analysis of specific IgE antibodies against tightly defined molecules (components) that constitute the allergen. Component-resolved diagnostics is particularly valuable in peanut allergy diagnosis, helping to determine allergen components associated with severe reactions. It also aids in predicting the course of the allergy and enables the development of personalized immunotherapy plans; however, the full application of it for these purposes still requires more precise studies. In this paper, we present the current knowledge about peanut allergy and component-resolved diagnostics possibilities. We discuss the possibilities of using molecular diagnostics in the diagnosis of peanut allergy. We focus on examining and predicting the development of peanut allergy, including the risk of anaphylaxis, and describe the latest data related to desensitization to peanuts.

EAACI Molecular Allergology User's Guide 2.0

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

Peanut-Induced Anaphylaxis in Children: A Literature Review

Peanut allergy has become more common among children and is considered one of the most common triggers for fatal anaphylaxis. Treatment of symptoms during a reaction is only one aspect of managing anaphylaxis; other elements include rigorous dietary avoidance and education about settings that could put the patient at a high risk of unintentional exposure. We aimed to review the prevalence, mechanism, diagnosis, treatment, and emergency action of peanut-induced anaphylaxis among children. We used a web-based literature search using the advanced features of databases such as PubMed, Scopus, Directory of Open Access Journals (DOAJ), Embase, Google Scholar, and Cochrane electronic databases. The most common food to cause fatal anaphylaxis and a common cause of food allergies is peanuts. Over the past two years, our knowledge improved more about peanut allergens, their prevalence, causes, diagnoses, and treatments. The research cited in this review demonstrates that the peanut allergens are most closely associated with disease differ across cultures, that early oral peanut exposure may reduce the occurrence of peanut allergy while early non-oral exposure may have the opposite effect, that complement activation by peanut constituents appears to promote peanut-induced anaphylaxis, and that oral immunotherapy, anti-IgE antibody, and a herbal formulation are all demonstrating promise as treatments. To conclude, peanut allergies have increased frequently during the past 10 years, especially in Westernized nations. Given that peanut allergy poses a danger for fatal anaphylaxis, response management is crucial. The current standard of care for those with nut allergies comprises complete food avoidance and the administration of injectable epinephrine to treat systemic symptoms.

BSACI guideline for the diagnosis and management of pollen food syndrome in the UK

Pollen food syndrome (PFS) is a highly prevalent food allergy affecting pollen-sensitized children and adults. Sufferers experience allergic symptoms when consuming raw plant foods, due to the homology between the pollen allergens and unstable proteins in these foods. The triggers involved can vary depending on the pollen sensitization, which in turn is affected by geographical location. The British Society of Allergy and Clinical Immunology (BSACI) Standards of Care Committee (SOCC) identified a need to develop a guideline for the diagnosis and management of PFS in the United Kingdom (UK). Guidelines produced by the BSACI use either the GRADE or SIGN methodology; due to a lack of high-quality evidence these recommendations were formulated using the SIGN guidelines, which is acknowledged to be less robust than the GRADE approach. The correct diagnosis of PFS ensures the avoidance of a misdiagnosis of a primary peanut or tree nut allergy or confusion with another plant food allergy to non-specific lipid transfer proteins. The characteristic foods involved, and rapid-onset oropharyngeal symptoms, mean PFS can often be diagnosed from the clinical history alone. However, reactions involving tree nuts, peanuts and soya milk or severe/atypical reactions to fruits and vegetables may require additional diagnostic tests. Management is through the exclusion of known trigger foods, which may appear to be simple, but is highly problematic if coupled with a pre-existing food allergy or for individuals following a vegetarian/vegan diet. Immunotherapy to pollens is not an effective treatment for PFS, and although oral or sublingual immunotherapy to foods seems more promising, large, controlled studies are needed. The typically mild symptoms of PFS can lead to an erroneous perception that this condition is always easily managed, but severe reactions can occur, and anxiety about the onset of symptoms to new foods can have a profound effect on quality of life.

Peanut components measured by ISAC: comparison with ImmunoCap and clinical relevance in peanut allergic children

Background

Specific IgE (sIgE) against the peanut component Arachis hypogaea (Ara h) 2 has been shown to be the most important allergen to discriminate between peanut allergy and peanut tolerance. Several studies determined sIgE cut off values for Ara h 2, determined by singleplex measurements. However, cut off values for Ara h 2 from multiplex arrays are less well defined. The aim of this study was to evaluate the correlation between Ara h 2 sIgE determined by singleplex versus multiplex measurements and to assess the diagnostic value of the different peanut components included in Immuno Solid-phase Allergen Chip (ISAC) multiplex analysis in children with a suspected peanut allergy.

Methods

In this retrospective study we analyzed Ara h 2 sIgE values with singleplex Fluorescence Enzyme Immunoassay (FEIA, ImmunoCap) and multiplex microarray (ISAC) measurements in 117 children with a suspected peanut allergy. Also, other peanut components measured by ISAC were analyzed. Double blinded placebo controlled oral food challenges were used as golden standard.

Results

Among all studied peanut components FEIA Ara h 2 sIgE showed the highest area under the curve (AUC, 0.922), followed by ISAC Ara h 6 and Ara h 2 sIgE with AUCs of respectively 0.906 and 0.902. Best cut off values to diagnose peanut allergy were 4.40 kU/l for FEIA Ara h 2 sIgE and, 7.43 ISU and 8.13 ISU for respectively Ara h 2 and Ara h 6 sIgE in ISAC microarray. Ara h 2 sIgE determined in FEIA and ISAC showed a good correlation (r = 0.88; p < 0.01).

Conclusion

Ara h 6 and Ara h 2 sIgE in multiplex ISAC are both good predictors of clinical peanut allergy in Dutch children, and their performance is comparable to the use of Ara h 2 in singleplex FEIA. The simultaneous measurement of different peanut components using ISAC is an advantage and clinically useful to detect peanut allergic children that are Ara h 2 negative but sensitized to other peanut proteins such as Ara h 6.

Identification of Pru du 6 as a potential marker allergen for almond allergy

BACKGROUND

Oral food challenges have demonstrated that diagnosis of almond allergy based on extract-sIgE tests displays low specificity. Molecular allergy diagnosis is expected to improve accuracy, but its value in diagnosing almond allergy remains unknown. The aim of this study was to identify relevant almond allergens and examine their ability to improve almond allergy diagnosis.

METHODS

IgE-reactive proteins were purified from almond kernels. IgE binding to almond extract and the allergens was analyzed by quantitative ELISA using sera from 18 subjects with a proven almond allergy. The control group consisted of sera from 18 subjects allergic to peanut and/or tree nuts but tolerant to almond.

RESULTS

Three IgE-binding proteins were identified: legumin (Pru du 6), alpha-hairpinin (Pru du 8), and mandelonitrile lyase (Pru du 10). Positive IgE (≥0.35 kU/L) to almond extract showed 94% sensitivity but only 33% specificity. IgE to Pru du 6 maintained high sensitivity (83%) and provided superior specificity (78%). Sera from almond-allergic subjects had significantly higher IgE levels to almond extract (P < .0001) and Pru du 6 (P < .0001) than sera from tolerant donors. Sensitization to Pru du 6 was highly specific for almond allergy, while frequencies of sensitization to legumins from peanut, walnut, hazelnut, and cashew were similar in both groups. IgE to Pru du 8 and Pru du 10 was less sensitive (41% and 67%), but showed specificities of 100% and 61%.

CONCLUSION

The use of almond allergens markedly increases the diagnostic specificity compared to the extract. Pru du 6 is a potential new molecular marker for almond allergy.

ImmunoCAP ISAC in food allergy diagnosis: a systematic review of diagnostic test accuracy

OBJECTIVE

To assess the diagnostic test accuracy of the component-resolved diagnosis device ImmunoCAP ISAC, compared with oral food challenge.

DESIGN

Systematic review reported according to the PRISMA-DTA recommendations.

DATA SOURCES

Medline, Embase and Cochrane Library databases were searched from inception to May 2019 and updated in March 2021.

ELIGIBILITY CRITERIA FOR SELECTING STUDIES

We included diagnostic test accuracy studies comparing ISAC component results as the index test with oral food challenge as the reference test, in people of any age suspected of IgE mediated food allergy to milk, egg, peanut, shrimp, hake, apple, peach, kiwi, melon, walnut, hazelnut, wheat or pineapple. Risk of bias was evaluated using the QUADAS-2 tool.

RESULTS

We screened 799 titles and included 11 studies - seven prospective and two retrospective cohort studies, two case-control studies. Included studies evaluated IgE to Gald1 (three studies, 300 participants, 140 with egg allergy), Bosd5 (three studies, 242 participants, 146 with milk allergy) and Arah1 or 2 (seven studies, 546 participants, 346 with peanut allergy). No studies were identified for other ISAC components. Risk of bias was high or unclear mainly due to inadequate blinding. Applicability was of high or unclear concern due to unclear thresholds, inappropriate exclusions and variable populations. Gald1 sensitivity ranged from 58 to 84%, specificity 87%-97%. Bosd5 sensitivity 24%-40%, specificity 94%-95%. Arah1 sensitivity 45%-91%, specificity 41%-93%. Arah2 sensitivity 70%-94%, specificity 75%-95%.

CONCLUSIONS

Diagnostic test accuracy information for ISAC components was only available for milk, egg and peanut. Specificity is generally higher than sensitivity, which contrasts with the performance of skin prick and standard specific IgE tests for diagnosing food allergy. Higher quality information is needed to determine the clinical utility of ISAC for food allergy diagnosis.

SYSTEMATIC REVIEW REGISTRATION

Not registered.

Ranking of 10 legumes according to the prevalence of sensitization as a parameter to characterize allergenic proteins

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10 different legumes extracts could be ranked based on the variations in the prevalence of sensitization.

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Variations in the prevalence of sensitization allowed for ranking of 18 different individual legume proteins.

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Ranking can be used to select reference proteins to develop predictive assays for the assessment of the sensitizing potential of novel proteins.

Predicting the allergenicity of novel proteins is challenging due to the absence of validated predictive methods and a well-defined reference set of proteins. The prevalence of sensitization could be a parameter to select reference proteins to characterize allergenic proteins. This study investigated whether the prevalence of sensitization of legume extracts and proteins can indeed be used for this purpose. A random sample of suspected food-allergic patients (n=106) was therefore selected. 10 extracts (processed and non-processed) and 18 individual proteins (2S albumins, 7S and 11S globulins) from black lentil, blue and white lupine, chickpea, faba bean, green lentil, pea, peanut, soybean, and white bean were isolated and the prevalence of sensitization and the intensity of IgE binding were evaluated. The prevalence of sensitization ranged from 5.7 % (faba bean and green lentil) to 14.2 % (peanut). The prevalence of sensitization for individual legume proteins ranged from 0.0 % for albumin 1 (pea) to 15.1 %–17.9 % for Ara h 1, 2, 3, and 6 (peanut). The prevalence of sensitization correlated strongly with the intensity of IgE binding for individual proteins (p < 0.05, ρ = 0.894), for extracts no correlation was found. The discovered ranking can be used to select reference proteins for the development and validation of predictive in vitro or in vivo assays for the assessment of the sensitizing potential.

Recent advances in the management of nut allergy

Peanut/tree nut allergy is common and has been associated with particularly severe reactions. Epidemiological data have shown that the prevalence ranges between 0.05% and 4.9% for tree nut and between 0.5% and 3% for peanut. These large variations can be explained by differences in the age of included patients and the geographical region. In addition, the food consumption modality (ie, raw versus roasted) plays a major role, as heat treatment has the capacity to modify the allergenicity of nuts and legumes. Nut allergies tend to persist into adulthood and consequently have a high impact on quality of life.

Recently, it has been demonstrated that a significant proportion of nut allergic patients are able to tolerate other nuts. As opposed to the avoidance of all nuts, this approach is currently proposed in several tertiary allergy centers. However, diagnosis of nut allergy is particularly difficult due to co-sensitization leading to high rate of false positive skin prick tests and/or specific IgE to whole allergen extracts. The use of component resolved diagnosis leads to major improvement of diagnosis, particularly to distinguish between primary and secondary nut allergies. The basophil activation test has been suggested to be useful but is still used mainly as a research tool. Thus, diagnosis remains mainly based on the oral food challenge, which is considered as the gold standard.

Regarding treatment, avoidance remains the cornerstone of management of nut allergy. Oral immunotherapy is increasingly proposed as an alternative management strategy.

Developments in the field of clinical allergy in 2018 through the eyes of Clinical and Experimental Allergy, Part II

In this article, we describe developments in the field of clinical allergy as described by Clinical and Experimental Allergy in 2018; epidemiology, asthma and rhinitis, clinical allergy and allergens are all covered.

Epitopes with similar physicochemical properties contribute to cross reactivity between peanut and tree nuts

Many individuals with peanut (PN) allergy have severe reactions to tree nuts (TN) such as walnuts or cashews. Although allergenic proteins in TN and PN have overall low identity, they share discrete sequences similar in physicochemical properties (PCP) to known IgE epitopes. Here, PCP-consensus peptides (cp, 13 aa and 31 aa) were identified from an alignment of epitope rich regions of walnut vicilin, Jug r 2, leader sequence (J2LS) and cross-reactive epitopes in the 2S albumins of peanut and synthesized. A peptide similarity search in the Structural Database of Allergenic Proteins (SDAP) revealed a network of peptides similar (low property distance, PD) to the 13 aa cp (13cp) in many different plant allergens. Peptides similar to the 13cp in PN and TN allergens bound IgE from sera of patients allergic to PN and TN in peptide microarray analysis. The 13cp was used to produce a rabbit consensus peptide antibody (cpAB) that detected proteins containing repeats similar to the 13cp in western blots of various nut extracts, in which reactive proteins were identified by mass spectrometry. The cpAB bound more specifically to allergens and nut extracts containing multiple repeats similar to the 13 cp, such as almond (Pru du 6), peanut (Ara h 2) and walnut (Jug r 2). IgE binding to various nut extracts is inhibited by recombinant J2LS sequence and synthetic 31cp. Thus, several repeated sequences similar to the 13cp are bound by IgE. Multiple similar repeats in several allergens could account for reaction severity and clinically relevant cross-reactivity to PN and TN. These findings may help improve detection, diagnostic, and therapeutic tools.

Prevalence and natural history of tree nut allergy

OBJECTIVE

Tree nuts are common causes of food-related allergic reactions and anaphylaxis. Resolution of tree nut allergy is thought to be low, yet studies of the natural history of tree nut allergy are limited. This review summarizes the available literature regarding tree nut allergy prevalence and natural history and discusses emerging diagnostic and prognostic developments that will inform clinical management of tree nut allergy.

DATA SOURCES

A comprehensive literature search using PubMed was performed.

STUDY SELECTIONS

Peer-reviewed publications relating to tree nut allergy prevalence, resolution, and diagnosis were selected, and findings were summarized using a narrative approach.

RESULTS

Tree nut allergy prevalence varies by age, region, and food allergy definition, and ranges from less than 1% to approximately 3% worldwide. Reports on the natural history of tree nut allergy data are limited to retrospective clinical data or cross-sectional survey data of self-reported food allergy, with reported resolution ranging from 9% to 14%. Component-resolved diagnostics and basophil activation testing offer the potential to improve the diagnostic accuracy and predicted prognosis of specific tree nut allergy, but studies are limited.

CONCLUSION

Tree nut allergy remains an understudied area of food allergy research with limited region-specific studies based on robust food allergy measures in population cohorts with longitudinal follow-up. This currently limits our understanding of tree nut allergy prognosis.

Real-world tree nut consumption in peanut-allergic individuals

BACKGROUND

Individuals with peanut allergy often avoid tree nuts, yet true rates of tree nut allergy in peanut-allergic individuals are as low as 7%.

OBJECTIVE

To examine tree nut sensitization patterns in peanut-allergic individuals, patient and family choice regarding tree nut consumption, and factors that influence consumption of tree nuts.

METHODS

All patients presenting for peanut allergy evaluation to an outpatient allergy office were included during a 4-month period. In addition to demographic information, sensitization to tree nuts and tree nut consumption were collected. Logistic regression was performed to generate odds ratios with 95% CIs in univariate and multivariate analyses for variables that predict tree nut consumption.

RESULTS

A total of 258 individuals with peanut allergy were enrolled. Ninety-five (36.8%) consumed all tree nuts ad libitum, 63 (24.4%) consumed some but not all tree nuts, and 100 (38.8%) consumed no tree nuts. Of the 100 electively avoiding all tree nuts, the most commonly reported reason was fear of cross-contact (50%). Although there was no difference between rates of sensitization between individual tree nuts (P = .056), cashew and pistachio had higher serum specific IgE levels compared with other tree nuts (P < .001). The tree nut most commonly consumed by peanut-allergic individuals was almond (P < .001). Consumption of foods with precautionary labeling was the strongest predictor of tree nut consumption in peanut allergic individuals (P < .001) CONCLUSION: Our data highlight the potential for safe introduction of tree nuts in peanut-allergic individuals and indicate that peanut-allergic individuals who consume foods with precautionary labeling are most likely to consume tree nuts.

Food allergy endotype with high risk of severe anaphylaxis in children-Monosensitization to cashew 2S albumin Ana o 3

BACKGROUND

Food allergy in children can be life-threatening. Component-resolved diagnostics approach to food anaphylaxis is rarely assessed in children. The aim of the study was to identify the food allergen components as the triggers responsible for severe anaphylaxis, with regard to characteristics and associated risks, among children in a large, population-based setting.

METHODS

Two hundred and seventy-one children who were hospitalized due to systemic allergic reaction (SAR) and food anaphylaxis were recruited. Medical history was assessed, and culprit allergen source and anaphylaxis severity grade were established. Specific IgE to 112 allergen components using multiplex ImmunoCAP ISAC immunoassay and specific IgE to hazelnut, Cor a 14, and cashew, Ana o 3, using singleplex ImmunoCAP immunoassay were determined.

RESULTS

We analyzed data from 237 SAR/anaphylaxis in 237 children. Trigger at allergen component level was defined for every episode. The most common triggers of SAR/anaphylaxis were seeds (50.6%), among them, the storage proteins. Anaphylaxis triggered by Ana o 3, 2S albumin from cashews (aOR = 15.0; 95% CI: 3.27 to 73.47); Tri a 19 from wheat (aOR = 9.93; 95% CI: 1.73 to 56.97); and Cor a 9 from hazelnut (aOR = 6.53; 95% CI: 1.16 to 36.72) had the worst clinical presentation including cardiovascular and severe respiratory symptoms (grade IV-V vs I-III in Cox scale). Thirteen out of 237 (5.5%) SAR/anaphylaxis patients were triggered by Ana o 3. Almost 82% of patients with severe Ana o 3 anaphylaxis were sensitized only to this component and had no concomitant food sensitization.

CONCLUSION

Monosensitization to Ana o 3 is, irrespective of other parameters, connected with high risk of severe anaphylaxis.

Component-Resolved Diagnosis in Food Allergies

Component-resolved diagnostics (CRD) in food allergies is an approach utilized to characterize the molecular components of each allergen involved in a specific IgE (sIgE)-mediated response. In the clinical practice, CRD can improve diagnostic accuracy and assist the physician in many aspects of the allergy work-up. CRD allows for discriminatory co-sensitization versus cross-sensitization phenomena and can be useful to stratify the clinical risk associated with a specific sensitization pattern, in addition to the oral food challenge (OFC). Despite this, there are still some unmet needs, such as the risk of over-prescribing unnecessary elimination diets and adrenaline auto-injectors. Moreover, up until now, none of the identified sIgE cutoff have shown a specificity and sensitivity profile as accurate as the OFC, which is the gold standard in diagnosing food allergies. In light of this, the aim of this review is to summarize the most relevant concepts in the field of CRD in food allergy and to provide a practical approach useful in clinical practice.

Recent advances in understanding and preventing peanut and tree nut hypersensitivity

Peanut allergy, the most persistent and deadly of the food allergies, has become more prevalent worldwide in recent decades. Numerous explanations have been offered for the rise in peanut allergy, which has been more pronounced in Western, industrialized nations. In infants who are at increased risk of peanut allergy, new evidence indicates that early introduction of peanuts can help prevent allergy development. This counterintuitive finding directly contradicts the previously established practice of peanut avoidance for high-risk infants but is supported by clinical and basic science evidence. Here, we review the literature contributing to our evolving understanding of nut allergy, emphasizing the translation of this work to clinical practice.

Legume Protein Consumption and the Prevalence of Legume Sensitization

Sensitization and allergy to legumes can be influenced by different factors, such as exposure, geographical background, and food processing. Sensitization and the allergic response to legumes differs considerably, however, the reason behind this is not yet fully understood. The aim of this study is to investigate if there is a correlation between legume protein consumption and the prevalence of legume sensitization. Furthermore, the association between sensitization to specific peanut allergens and their concentration in peanut is investigated. Legume sensitization data (peanut, soybean, lupin, lentil, and pea) from studies were analyzed in relation to consumption data obtained from national food consumption surveys using the European Food Safety Authority (EFSA), Global Environment Monitoring System (GEMS), and What We Eat in America-Food Commodity Intake Database (WWEIA-FCID) databases. Data were stratified for children <4 years, children 4⁻18 years, and adults. Sufficient data were available for peanut to allow for statistical analysis. Analysis of all age groups together resulted in a low correlation between peanut sensitization and relative peanut consumption (r = 0.407), absolute peanut consumption (r = 0.468), and percentage of peanut consumers (r = 0.243). No correlation was found between relative concentrations of Ara h 1, 2, 3, 6, 7, and 8 in peanut and sensitization to these peanut allergens. The results indicate that the amount of consumption only plays a minor role in the prevalence of sensitization to peanut. Other factors, such as the intrinsic properties of the different proteins, processing, matrix, frequency, timing and route of exposure, and patient factors might play a more substantial role in the prevalence of peanut sensitization.

Sensitization profiles to hazelnut allergens across the United States

BACKGROUND

Measurement of IgE antibody to hazelnut components can aid in the prediction of allergic responses to the food.

OBJECTIVE

To investigate the association between patient demographics (age, location) and patterns of allergic sensitization to hazelnut components across the United States and to investigate the degree of correlation between hazelnut sensitization with sensitization to other tree nuts, peanuts, and their components.

METHODS

Serum samples from 10,503 individuals with hazelnut extract specific IgE (sIgE) levels of 0.35 kU_A/L or higher were analyzed for IgE antibodies to Cor a 1, 8, 9, and 14 by ImmunoCAP. A subset of these patients were analyzed for IgE antibodies to peanut, walnut, and cashew nut IgE along with associated components.

RESULTS

Among hazelnut sensitized individuals, children (<3 years old) were predominantly sensitized to Cor a 9 and Cor a 14. Conversely, Cor a 1 sIgE sensitization was much higher in adults than children, especially in the Northeastern United States. Cor a 8 sensitization was relatively constant (near 10%) across all ages. Cosensitization of hazelnut with other tree nuts and peanuts was related to correlation of IgE concentrations of individual component families.

CONCLUSION

We conclude that sensitization to individual hazelnut components is highly dependent on age and/or geographic location. Component correlations suggest that cosensitization to hazelnut and walnut may be caused by their pathogenesis-related protein 10 allergens, nonspecific lipid transfer proteins, or seed storage proteins, whereas hazelnut and peanut cosensitization is more often caused by cross-reactivity of pathogenesis-related protein 10 (Cor a 1 and Ara h 8) and nonspecific lipid transfer proteins (Cor a 8 and Ara h 9).

Allergy diagnosis from symptoms to molecules, or from molecules to symptoms: a comparative clinical study

Background

Classical allergy diagnostic workup “from symptoms to molecules” comprises 1) clinical investigation, 2) skin prick- and IgE- testing, and recently, 3) molecular allergy testing. We aimed to examine the diagnostic fidelity of the alternative approach “from molecules to symptoms”, which was recently suggested in the EAACI Molecular Allergology User’s Guide, in a retrospective clinical study.

Methods

Records from 202 patients with clinically suspected allergic sensitizations were extracted from files at two sites applying either the “ISAC-first” workup with IgE-testing by immuno-solid phase allergen chip ISAC112 followed by selected skin prick tests (SPT) or the “SPT-first” starting with SPT followed by the microarray test.

Results

In the ISAC-first procedure significantly less SPTs were performed during allergy diagnosis (median 4 vs. 14). By SPT in 19% of patients in the ISAC-first group and in 34% in the SPT-first group additional respiratory allergens (p = 0.014) were detected not positive in ISAC microarray. By ISAC microarray test 18% additional sensitizations were found in the ISAC-first, and 32% in SPT-first cohort (p = 0.016). For food allergens 13 and 12% additional sensitizations were detected by the microarray not detected by SPT in the two groups (p = 0.800). No additional food allergen was found by SPT in the ISAC-first group, while in 6% of the cases in the SPT-first group detected sensitizations were negative in the microarray.

Discussion

The ISAC-first approach followed by (fewer) SPTs meets the demands for a patient’s tailored diagnostic work-up and therefore can be considered equivalent to the conventional way using the skin prick test as first screening tool, followed by IgE diagnosis.

Conclusions

For the diagnostic verification of clinically suspected allergy, the novel concept “from molecules to clinic” offers a reliable diagnostic workup in shorter time. Due to lower skin test numbers it is especially applicable for young children and seniors, in atopic patients, and whenever skin tests get difficult or unreliable.

Electronic supplementary material

The online version of this article (10.1186/s40413-018-0199-y) contains supplementary material, which is available to authorized users.

Tree nut allergies: Allergen homology, cross-reactivity, and implications for therapy

Tree nut allergy is a potentially life-threatening disease that is increasing in prevalence, now affecting 1% of the general population in the United States. While other food allergies often resolve spontaneously, tree nut allergies are outgrown in less than 10% of cases. Due to the likelihood of cross-sensitization to multiple tree nut allergens, the current treatment guideline is strict avoidance of all nuts once one tree nut allergy has been diagnosed. For example, walnut and pecan are highly cross-reactive, along with cashew and pistachio, but the extent of clinical, IgE-mediated cross-reactivity among other tree nuts remains unclear, therefore making avoidance of all tree nuts a safe approach. There have been recent advances in immunotherapy for food allergies. For instance, there are investigational immunotherapies for milk, egg and peanut allergies, specifically oral immunotherapy, sublingual immunotherapy and epicutaneous immunotherapy. However, there are no large randomized controlled clinical trials for tree nut allergies. Even though there has been less research into tree nut allergy immunotherapies, the evidence of T-cell cross-reactivity among tree nuts exists in animal models and in T cells from allergic patients indicates that immunotherapeutic interventions may be possible. Here, we review the literature regarding epidemiology, allergen homology and cross-reactivity among tree nuts, and explore how current findings can be employed for effective therapy.