The use of serum-specific IgE measurements for the diagnosis of peanut, tree nut, and seed allergy

Murine model of cross-IgE sensitization and cross-anaphylactic reactions among multiple group food allergens

Rationale

Approximately 32 million people in the United States suffer from food allergies. Some food groups, such as legumes - peanuts, tree nuts, fish, and shellfish, have a high risk of cross-reactivity. However, the murine model of multiple food group cross-reactivity is limited.

Objective

We sought to develop a murine model that can be used to investigate novel therapeutics for the treatment of multiple food allergies.

Methods

C3H/HeJ mice were sensitized intraperitoneally (i.p.) once a week for three weeks with a mixture of 500µg of protein from peanut, cashew, walnut, shrimp, cod, and 2 mg Alum. The control group consisted of naïve mice. IgE levels against the sensitized allergens and their cross-reactive allergens were measured by ELISA at baseline and 3 weeks after sensitization. In weeks 4 and 5, the mice were given intragastric challenges with 200mg/mouse of each food: peanut, chickpea, lentil, cashew, almond, pistachio, hazelnut, brazil nut, walnut, pecan, shrimp, lobster, cod, salmon, and mackerel. After each challenge, anaphylactic symptoms, rectal temperatures, and plasma histamine were measured.

Results

There was a significant elevation of IgE against sensitized antigens (peanut cashew, walnut, shrimp, and cod) as well as cross-reactive allergens used for oral food challenge from legumes including peanut, chickpea, and lentil, as well as tree nuts such as cashew, almond, pistachio, hazelnut, brazil nut, walnut, and pecan. Furthermore, there was a significant increase in crustaceans such as shrimp, lobster and fish like cod, salmon, and mackerel (p<0.01). Consistently, significantly increased anaphylactic symptom scores (p<0.05), decreased rectal temperature (p<0.001), and increased plasma histamine (p<0.05) compared to the naïve mice occurred following each challenge with sensitized foods and unsensitized, but cross-reactive foods.

Conclusion

We generated a comprehensive murine model of IgE-mediated multiple food groups of cross-reactive anaphylaxes. This will provide an essential tool for developing novel therapies for cross-reactivity multiple food allergies.

Tree Nut Allergy in Children-What Do We Know? -A Review

Food allergy represents a significant public health concern, with its prevalence increasing in recent decades. Tree nuts are among major allergenic foods, and allergies to them are frequently linked to severe and potentially life-threatening reactions. Data on the prevalence and natural history of tree nut allergy are limited. Primary nut allergy typically presents with rapid-onset IgE-mediated symptoms. Diagnosis can be confirmed by demonstrating a positive skin prick test (SPT), specific IgE (sIgE), or through an oral food challenge. Component-resolved diagnostics (CRD) can identify those with a high risk of anaphylaxis. The main management strategy involves avoiding the culprit allergen and treating symptoms after accidental exposure. New therapeutic options, such as sublingual immunotherapy, oral food immunotherapy, with or without omalizumab, and other monoclonal antibodies, are being investigated to modify tree nut allergy. Tree nut allergy is a lifelong disease with a low likelihood of resolution. The aim of this paper is to present the current data on the prevalence, diagnosis, natural history, and management options for tree nut allergy.

AAAAI-EAACI PRACTALL: Standardizing oral food challenges-2024 Update

This common statement of the American Academy of Allergy, Asthma and Immunology (AAAAI) and The European Academy of Allergy and Clinical Immunology (EAACI) provides an update of the 2012 published guidelines on food challenges. The guidelines equally address food challenges in the research and the clinical settings. They first address the diagnostic tests which can guide the decision to conduct a challenge. Safety of food challenges is prime, and the various procedures and safety issues as well as medications potentially involved in challenges are extensively discussed. Challenges are suggested to be conducted with semi-logarithmic incremental doses based on the protein content, typically for IgE-mediated food allergy with intervals of 20-30 min between doses. Specific protocols for other types of reactions such atopic dermatitis or gastrointestinal food allergy are detailed separately. Proper stopping criteria are essential in order to reduce the risk of false-positive diagnoses, but also severe reactions. The guidelines recommend criteria based on "go on," "stop," or "observation." These revised guidelines will clearly provide much needed guidance for food challenges in the research and clinical settings. They will continue to evolve with new diagnostic tests or new needs in the field of food allergy.

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

INTRODUCTION

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

AREAS COVERED

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

EXPERT OPINION

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

Recognition of nuts and seeds in children with/without food allergies and their mothers: A reflection of culinary culture

BACKGROUND

Nuts and seeds are among the leading causes of food allergy. Effective food allergy management hinges on the ability to identify and avoid relevant foods.

AIM

To evaluate the nut/seed recognition ability in both children and mothers.

METHODS

Primary caregivers (mothers) and their children (6-18 years old) with/without food allergies were shown photographs of nuts/seeds, and their products with visible/hidden allergens to assess their ability to recognize accurately.

RESULTS

A total of 196 children and 184 mothers participated. The median ages of the children and mothers were 7.6 (6.8-10) and 37.8 (33.1-41.5) years, respectively. Over 75% of the children/adolescents and over 90% of the mothers accurately identified the kernel forms of nuts/seeds, except pine nuts. Walnuts, hazelnuts, almonds, and cashews were the most accurately recognized kernel forms by both populations. Generally, the kernel forms were recognized 5-20% more accurately than their in-shell forms, followed by products with visible and hidden forms, respectively. Some Turkish culinary-specific products with visible/hidden allergens were recognized as frequently as the kernel/in-shell forms by both study groups. Although there was a similar recognition pattern between study groups and subgroups (nut/seed allergy, other food allergy, controls), higher rates of recognition were found in mothers than in their children and adolescents than in schoolchildren.

CONCLUSION

In Eastern Mediterranean region, nuts and sesame seeds are highly recognized by both mothers and their children. Accurate identification of these foods is likely a culinary feature, but not the result of increased awareness. More information is needed on whether this ability reduces the risk of exposure.

Alanine Scanning of the Unstructured Region of Ara h 2 and of a Related Mimotope Reveals Critical Amino Acids for IgE Binding

SCOPE

The unstructured region of Ara h 2, referred to as epitope 3, contains a repeated motif, DYPSh (h = hydroxyproline) that is important for IgE binding.

METHODS AND RESULTS

IgE binding assays to 20mer and shorter peptides of epitope 3, defines a 16mer core sequence containing one copy of the DPYSh motif, DEDSYERDPYShSQDP. This study performs alanine scanning of this and a related 12mer mimotope, LLDPYAhRAWTK. IgE binding, using a pool of 10 sera and with individual sera, is greatly reduced when alanine is substituted for aspartate at position 8 (D8; p < 0.01), tyrosine at position 10 (Y10; p < 0.01), and hydroxyproline at position 12 (h12; p < 0.001). IgE binding to alanine-substituted peptides of a mimotope containing the DPY_h motif confirm the critical importance of Y (p < 0.01) and h (p < 0.01), but not D. Molecular modeling of the core and mimotope suggests an h-dependent conformational basis for the recognition of these sequences by polyclonal IgE.

CONCLUSIONS

IgE from pooled sera and individual sera differentially bound amino acids throughout the sequences of Epitope 3 and its mimotope, with Y10 and h12 being most important for all sera. These results are highly significant for designing hypoallergenic forms of Ara h 2.

Cashew Allergy Prevalence and Sensitization in 1-Year-Old Infants

BACKGROUND

Cashew allergy is the most common tree nut allergy in Australia, but there are limited data on the population-level prevalence and risk factors.

OBJECTIVE

Describe the prevalence of cashew sensitization and allergy in 12-month-old infants and identify risk factors.

METHODS

Data were from the EarlyNuts cohort, a population-based sample of infants recruited in Melbourne, Australia. Families completed a questionnaire and infants underwent a skin prick test (SPT) to cashew. Infants with positive SPTs were offered food challenges. Questionnaires collected demographic data and allergy risk factors. Allergy outcomes were determined by challenge outcomes or a convincing history of an allergic reaction. We used weights to adjust estimated prevalence to reflect the distribution of risk factors among the combined sample of participants and nonparticipants.

RESULTS

We recruited 1,933 participants and identified 1,414 cashew allergy outcomes. Of these, 1.96% (95% CI, 1.28-2.99) had an SPT result of 3 mm or greater and 1.49% (95% CI, 0.91-2.44) were allergic to cashew. Infants with eczema or peanut allergy in the first year of life were more likely to be allergic to cashew (adjusted odds ratio = 5.75; 95% CI, 2.08-15.88; P = .001; and adjusted odds ratio = 19.30; 95% CI, 5.44-68.43; P < .001, respectively). Twenty-five percent of participants had cashew introduced before 12 months (95% CI, 22.7-27.8). There was no association between the timing of cashew introduction and cashew allergy.

CONCLUSIONS

To our knowledge, this is the first study describing the prevalence of and risk factors for cashew allergy in a population-based infant cohort. Eczema and peanut allergy were associated with an increased risk of cashew allergy. Few infants were introduced to cashew before age 12 months, which suggests that infant feeding guidelines have not yet translated to the earlier introduction of all allergens.

Leguminosas como causa infrecuente de alergia alimentaria en Colombia: reporte de dos casos y revisión de la literatura

La alergia alimentaria se ha venido incrementando a nivel mundial, afectando alrededor del 1,5 % a 2,5 % de los adultos y 6 % de los niños, y tiene un gran impacto en la calidad de vida de los pacientes y sus cuidadores, debido a las dietas de restricción. Los alérgenos más prevalentes son la leche, el huevo, el trigo, la soja, los frutos secos, el maní, el pescado y los mariscos. Las leguminosas mejor estudiadas son el maní y la soja; otras leguminosas como las lentejas, garbanzos y arvejas representan la quinta causa de alergia alimentaria en el área mediterránea, en Turquía y en la India, siendo menos prevalentes en otras áreas geográficas. La alergia a las leguminosas es una entidad infrecuente en Colombia, se desconoce la prevalencia en el país. Describimos los primeros dos casos de anafilaxia por lentejas reportados en el país. Ambos pacientes menores de 18 años, con reacciones adversas tras la ingesta de leguminosas, en las cuales se demuestra alergia mediada por IgE a las lentejas y además sensibilización en el primer caso a las arvejas y garbanzos, y en el segundo caso a los frijoles. Diferentes datos sobre la prevalencia se han descrito en varias áreas geográficas, siendo mayor en países con dietas mediterráneas. Las reacciones mediadas por IgE suelen aparecer incluso con el alimento altamente cocido, debido a la termo-estabilidad de las proteínas. La reactividad cruzada más frecuente se relaciona con los garbanzos y las arvejas.

Induction of food-specific IgG by Gene Gun-delivered DNA vaccines

Background

Shellfish and tree nut allergies are among the most prevalent food allergies, now affecting 2%–3% and 1% of the US population, respectively. Currently, there are no approved therapies for shellfish or tree nut allergies, with strict avoidance being the standard of care. However, oral immunotherapy for peanut allergy and subcutaneous immunotherapy for environmental allergens are efficacious and lead to the production of allergen-specific IgG, which causes suppression of allergen effector cell degranulation. Since allergen-specific IgG is a desired response to alleviate IgE-mediated allergies, we tested transcutaneously-delivered DNA vaccines targeting shellfish and tree nut allergens for their ability to induce antigen-specific IgG, which would have therapeutic potential for food allergies.

Methods

We assessed Gene Gun-delivered DNA vaccines targeting either crustacean shellfish or walnut/pecan allergens, with or without IL-12, in naïve mice. Three strains of mice, BALB/cJ, C3H/HeJ and CC027/GeniUnc, were evaluated for IgG production following vaccination. Vaccines were administered twice via Gene Gun, three weeks apart and then blood was collected three weeks following the final vaccination.

Results

Vaccination with shellfish allergen DNA led to increased shrimp-specific IgG in all three strains, with the highest production in C3H/HeJ from the vaccine alone, whereas the vaccine with IL-12 led to the highest IgG production in BALB/cJ and CC027/GeniUnc mice. Similar IgG production was also induced against lobster and crab allergens. For walnut/pecan vaccines, BALB/cJ and C3H/HeJ mice produced significantly higher walnut- and pecan-specific IgG with the vaccine alone compared to the vaccine with IL-12, while the CC027 mice made significantly higher IgG with the addition of IL-12. Notably, intramuscular administration of the vaccines did not lead to increased antigen-specific IgG production, indicating that Gene Gun administration is a superior delivery modality.

Conclusions

Overall, these data demonstrate the utility of DNA vaccines against two lifelong food allergies, shellfish and tree nuts, suggesting their potential as a food allergy therapy in the future.

IgE mediated legume allergy in east Mediterranean children: A reflection of multiple food allergies

BACKGROUND

Legumes are nutritionally valuable as an inexpensive protein source, but may cause severe allergic reactions. This study aimed to identify the characteristics of legume allergies (LAs) in Turkish children.

METHODS

A total of 87 children (4.9 (3.1-7.0) years) with LAs confirmed by either oral food challenge (OFC) or consistent history were reviewed.

RESULTS

The median age of onset was 19 (12-38) months. The most frequent LA was lentil (n = 57, 66%), followed by peanut (n = 53, 61%), chickpea (n = 24, 28%), pea (n = 21, 24%), bean (n = 7, 8%), and soybean (n = 1, 1%). From these, it was observed that 60% had multilegume (≥2) allergies and the age of onset occurred earlier compared with the single LA subgroup (18 (11-30) vs. 28 (17-42) months, p = .042). Single LA was present in peanut (51%) and lentil (16%) allergies, but not chickpea, pea, and bean. Fifteen patients had tolerated lentils before their first allergic reaction. The majority of children with LA (91.9%) were allergic to multiple foods including tree nuts (71%), hen's egg (66%), and cow's milk (49%). Seventy-eight patients (89.7%) also presented with atopic comorbidities concerning atopic dermatitis (70%), asthma (40%), and allergic rhinitis (30%). Patients with anaphylactic type of reaction (20%) had higher frequency of aeroallergen sensitization (p = .001). Lip dose challenge with legume paste predicted the result of OFC with a diagnostic accuracy of 81.82% and a positive likelihood ratio of 10.8.

CONCLUSION

In Turkey, LA is a reflection of multiple food allergies and the presence of allergy to a least frequently encountered legume is a sign of multiple LA.

Patterns of Clinical Reactivity in a Danish Cohort of Tree Nut Allergic Children, Adolescents, and Young Adults

Background

Tree nut allergy is associated with severe reactions and poly-sensitization to other nuts and peanuts often occurs. There are regional differences in sensitization profiles that result in differences in clinical presentation. Denmark is located in a birch pollen endemic area, which could influence the allergy patterns due to pollen cross-sensitization.

Objective

This study aimed to investigate patterns of sensitization and clinical reactivity to tree nuts and peanuts and threshold levels for oral food challenges (OFCs) in a Danish cohort of tree nut allergic children, adolescents, and young adults.

Methods

Forty tree nut allergic subjects were assessed for clinical reactivity to six nuts, i.e., hazelnut, walnut, pistachio, cashew, almond, and peanut, by OFCs or convincing medical history of an immediate allergic reaction or tolerance. Clinical presentation and allergen-specific immunoglobulin E (sIgE) levels together with eliciting dose and rescue medication in OFCs were furthermore assessed.

Results

Allergy to two or more tree nuts was observed in most cases. Hazelnut-walnut dual allergy was common but not exclusively observed as concomitant allergies. Allergy to cashew was coincided in all but one of the assessed subjects with pistachio allergy. Half of all assessed subjects were allergic to peanuts. Oral symptoms followed by a skin reaction were the most common symptomatology that lead to OFC cessation and subjects often presented with symptoms from two or more organ systems. OFC threshold levels were within the same range, but cashew was distinguished from other nuts by causing allergic symptoms at the lowest dose. Clinical reactivity and the allergy patterns were to some extent reflected by sIgE levels and by correlations in sIgE between the nuts.

Conclusions

In this Northern European cohort, subjects with clinically relevant tree nut allergy were generally allergic to two or more tree nuts and close to half of them also to peanuts. There were two distinct and independent allergic phenotypes; the majority of hazelnut allergic subjects were also allergic to walnut, and all but one subject with cashew allergy were dual allergic to pistachio. These findings are consistent with a strong sIgE correlation between hazelnut and walnut and a close to total sIgE correlation between cashew and pistachio.

Tree Nuts and Peanuts as a Source of Beneficial Compounds and a Threat for Allergic Consumers: Overview on Methods for Their Detection in Complex Food Products

Consumption of tree nuts and peanuts has considerably increased over the last decades due to their nutritional composition and the content of beneficial compounds. On the other hand, such widespread consumption worldwide has also generated a growing incidence of allergy in the sensitive population. Allergy to nuts and peanuts represents a global relevant problem, especially due to the risk of the ingestion of hidden allergens as a result of cross-contamination between production lines at industrial level occurring during food manufacturing. The present review provides insights on peanuts, almonds, and four nut allergens—namely hazelnuts, walnuts, cashew, and pistachios—that are likely to cross-contaminate different food commodities. The paper aims at covering both the biochemical aspect linked to the identified allergenic proteins for each allergen category and the different methodological approaches developed for allergens detection and identification. Attention has been also paid to mass spectrometry methods and to current efforts of the scientific community to identify a harmonized approach for allergens quantification through the detection of allergen markers.

Structure, Immunogenicity, and IgE Cross-Reactivity among Walnut and Peanut Vicilin-Buried Peptides

Vicilin-buried peptides (VBPs) from edible plants are derived from the N-terminal leader sequences (LSs) of seed storage proteins. VBPs are defined by a common α-hairpin fold mediated by conserved CxxxCx(10-14)CxxxC motifs. Here, peanut and walnut VBPs were characterized as potential mediators of both peanut/walnut allergenicity and cross-reactivity despite their low (∼17%) sequence identity. The structures of one peanut (AH1.1) and 3 walnut (JR2.1, JR2.2, JR2.3) VBPs were solved using solution NMR, revealing similar α-hairpin structures stabilized by disulfide bonds with high levels of surface similarity. Peptide microarrays identified several peptide sequences primarily on AH1.1 and JR2.1, which were recognized by peanut-, walnut-, and dual-allergic patient IgE, establishing these peanut and walnut VBPs as potential mediators of allergenicity and cross-reactivity. JR2.2 and JR2.3 displayed extreme resilience against endosomal digestion, potentially hindering epitope generation and likely contributing to their reduced allergic potential.

Associations of early-life pet ownership with asthma and allergic sensitization: a meta-analysis of >77,000 children from the EU Child Cohort Network

BACKGROUND

Studies examining associations of early-life cat and dog ownership with childhood asthma have reported inconsistent results. Several factors could explain these inconsistencies, including type of pet, timing and degree of exposure.

OBJECTIVE

To study associations of early-life cat and dog ownership with school-age asthma, including the role of type (cat versus dog), timing (never, prenatal or early childhood) and degree (number) of ownership, and the role of allergic sensitisation.

METHODS

We used harmonised data from 77,434 mother-child dyads aged 5-11 years from nine birth cohorts in the EU Child Cohort Network. Associations were examined through the DataSHIELD platform using adjusted logistic regression models, fitted separately for each cohort and combined using random-effects meta-analysis.

RESULTS

Early-life cat and dog ownership ranged between 12-45% and 7-47% respectively, and prevalence of asthma between 2-20%. There was no overall association between either cat or dog ownership and asthma (OR: 0.97 (95% CI: 0.87-1.09) and 0.92 (0.85-1.01), respectively). Timing and degree of ownership did not strongly influence associations. Cat and dog ownership were also not associated with cat- and dog-specific allergic sensitisation (OR: 0.92 (0.75-1.13) and 0.93 (0.57-1.54), respectively). However, cat- and dog-specific allergic sensitisation were strongly associated with school-age asthma (OR: 6.69 (4.91-9.10) and 5.98 (3.14-11.36), respectively). There was also some indication of an interaction between ownership and sensitisation, suggesting that ownership may exacerbate the risks associated with pet-specific sensitisation, but offer some protection against asthma in the absence of sensitisation.

CONCLUSION

Our findings do not support early-life cat and dog ownership in themselves increasing the risk of school-age asthma, but suggest that ownership may potentially exacerbate the risks associated with cat- and dog-specific allergic sensitisation.

Optimizing tools for evaluating challenge outcomes in children with cashew nut allergy

BACKGROUND

The incidence of cashew nut anaphylaxis is increasing and there is a need for accurate diagnostic tests. Age-specific cutoffs in children are lacking. Changes in serum tryptase levels are not well documented in pediatric food allergy, except in anaphylaxis.

OBJECTIVE

To evaluate the ability of various tests to diagnose cashew nut allergy and to predict reaction severity. We also investigated changes in tryptase and their correlation to reaction severity.

METHODS

We performed an open cashew nut challenge on 106 children (aged 1-16 years), who were sensitized to cashew nut with either previous allergic reaction to cashew nut or no known exposure. We analyzed the accuracy of Ana o 3 immunoglobulin E (IgE), cashew nut IgE, skin prick test, basophil activation test (BAT), and combinations thereof to diagnose cashew nut allergy and to predict reaction severity. Tryptase level was measured at the baseline and during an allergic reaction.

RESULTS

A total of 72 children had positive challenge outcomes. Ana o 3 IgE seemed to be the best single test to diagnose cashew allergy, with a 0.97 kU/L cutoff exhibiting 94.1% specificity and 61.1% sensitivity. Though BAT values of at least 22.8% best predicted reaction severity, with 91.7% specificity and 60.7% sensitivity, the cutoffs were age-specific. Tryptase levels increased substantially 1 to 2 hours after the first allergic symptoms compared with baseline.

CONCLUSION

Ana o 3 IgE seems to be the best diagnostic test in pediatric cashew nut allergy, and test combinations do not seem to improve the diagnostics. Cutoffs are age-specific. BAT is promising in predicting reaction severity. Tryptase levels should be measured 1 to 2 hours after initiation of an allergic reaction.

Adverse Events and Labeling Issues Related to Suspected Sesame Allergy Reported in an Online Survey

BACKGROUND

Allergen avoidance is critical for those with IgE-mediated food allergy (FA) but can only be successful with accurate product information. While the Food and Drug Administration (FDA) maintains the Center for Food Safety and Nutrition (CFSAN) Adverse Event Reporting System (CAERS) to collect adverse event (AE) reports related to foods, there is significant under-reporting and information regarding product labeling issues is limited.

OBJECTIVE

The purpose of this study was to describe allergic reactions associated with accidental oral exposure to sesame and the role of product labeling.

METHODS

A questionnaire was developed and disseminated to online communities focused on sesame allergy. The questionnaire included questions on clinical characteristics, treatments, outcomes, and labelling issues.

RESULTS

360 clinical reactions related to sesame were reviewed in 327 individuals. Anaphylaxis occurred in 68.9% of reactions. Hospitalization occurred in 47.8% of events and epinephrine was administered in 36.4% of cases. Events involving a packaged food-product occurred in 67.5% of AEs with only 43.8% of these using the term "sesame." An alternate name was noted in 46.0% of products that did not include "sesame" on labeling, most of which was "tahini".

CONCLUSION

We demonstrate considerable sesame FA morbidity in part due to inconsistent allergen labeling. Our findings support development of a swifter process for the FDA to update the major allergen list as well as formulation of an improved system for reporting AEs related to foods.

Nut Allergy: Clinical and Allergological Features in Italian Children

BACKGROUND

Nut allergies are an increasingly frequent health issue in the pediatric population. Tree nuts (TN) and peanuts are the second cause of food anaphylaxis in Italy. Unfortunately, knowledge of the clinical characteristics of a TN allergy in Italian children is limited. Our study aimed to identify the clinical and allergological characteristics of Italian children with a nut allergy (TN and peanut).

METHODS

A retrospective observational analysis was performed on the clinical charts of children with a history of nut reaction referred to the allergy unit of the hospital from 2015 to 2019. The studied population was represented by children with a confirmed nut allergy based on positive prick by prick and/or serum-specific IgE to nut plus a positive nut oral food challenge. Demographic, clinical, and allergological features were studied and compared among different nuts.

RESULTS

In total, 318 clinical charts were reviewed. Nut allergy was confirmed in 113 patients. Most patients (85/113, 75%) had a familial history of allergy and/or a concomitant allergic disorder (77/113, 68%). Hazelnut and walnut were the more common culprit nuts observed in allergic children. Anaphylaxis was the first clinical manifestation of nut allergy in a high percentage of children (54/113, 48%). The mean age of the first nut reaction was statistically higher with pine nuts. Over 75% of children reported a single nut reaction. During the OFCs, the signs and symptoms involved mainly the gastrointestinal system (82/113, 73%) and resolved spontaneously in most cases. Severe reactions were not frequent (22/113, 19%).

CONCLUSION

To our knowledge, this is the first Italian study that provided a comprehensive characterization of children with a nut allergy. These results are important for clinicians treating children with a nut allergy.

Diagnosis and Management of Food Allergy

Food allergy is an immune-mediated disease and must be differentiated from other adverse effects related to food that are non-immune mediated. Symptoms of immunoglobulin (Ig) E-mediated allergy can range from mild to severe, and life-threatening anaphylaxis may occur. Current recommended strategies for diagnosis include the use of skin prick tests, allergen-specific serum IgE, and/or oral food challenges. Management entails allergen avoidance and appropriate treatment of allergic reactions should accidental ingestions occur. Treatment approaches under investigation include immunotherapy as well as biologics and novel vaccines. Attention has also recently focused on implementing strategies for prevention of food allergy.

Effect of Sample Preparation on the Detection and Quantification of Selected Nuts Allergenic Proteins by LC-MS/MS

The detection and quantification of nut allergens remains a major challenge. The liquid chroma-tography tandem mass spectrometry (LC-MS/MS) is emerging as one of the most widely used methods, but sample preparation prior to the analysis is still a key issue. The objective of this work was to establish optimized protocols for extraction, tryptic digestion and LC-MS analysis of almond, cashew, hazelnut, peanut, pistachio and walnut samples. Ammonium bicar-bonate/urea extraction (Ambi/urea), SDS buffer extraction (SDS), polyvinylpolypyrroli-done (PVPP) extraction, trichloroacetic acid/acetone extraction (TCA/acetone) and chloro-form/methanol/sodium chloride precipitation (CM/NaCl) as well as the performances of con-ventional tryptic digestion and microwave-assisted breakdown were investigated. Overall, the protein extraction yields ranged from 14.9 ± 0.5 (almond extract from CM/NaCl) to 76.5 ± 1.3% (hazelnut extract from Ambi/urea). Electrophoretic profiling showed that the SDS extraction method clearly presented a high amount of extracted proteins in the range of 0-15 kDa, 15-35 kDa, 35-70 kDa and 70-250 kDa compared to the other methods. The linearity of the LC-MS methods in the range of 0 to 0.4 µg equivalent defatted nut flour was assessed and recovery of internal standards GWGG and DPLNV(d8)LKPR ranged from 80 to 120%. The identified bi-omarkers peptides were used to relatively quantifier selected allergenic protein form the inves-tigated nut samples. Considering the overall results, it can be concluded that SDS buffer allows a better protein extraction from almond, peanut and walnut samples while PVPP buffer is more appropriate for cashew, pistachio and hazelnut samples. It was also found that conventional overnight digestion is indicated for cashew, pistachio and hazelnut samples, while microwave assisted tryptic digestion is recommended for almond, hazelnut and peanut extracts.

Clinical Predictors and Outcomes of Oral Food Challenges Illustrate Differences Among Individual Tree Nuts

BACKGROUND

Although allergy to tree nuts is often considered a single entity, there is heterogeneity in patient reactivity and immune response to different tree nuts.

OBJECTIVE

We sought to characterize tree nut oral food challenges (OFCs) in a pediatric population performed at a single center over a 12-year period and determine differences in OFC outcome to different tree nuts.

METHODS

A retrospective chart review was conducted in patients (0-20 years) who completed an unblinded OFC to any tree nut from 2007 to 2019 at Lurie Chlildren's Hospital of Chicago. Differences among almond, cashew, hazelnut, and walnut challenges were compared, and probability curves were used to estimate positive predictive values (PPVs) of specific IgE at OFC.

RESULTS

A total of 531 tree nut OFCs were included. The mean age at OFC was 7.77 years (standard deviation, 4.33). Overall, 74.0% of children passed clinically indicated OFCs. Of the 4 most commonly challenged tree nuts, almost all patients passed OFC to almond (97.3%) and hazelnut (87.9%). Pass rates were lower for cashew (65.3%) and walnut (57.0%), P < .0001. The odds of failure were 0.83 times lower for patients who were avoiding without a previous reaction compared with those who had previously reacted (P = .0025).

CONCLUSIONS

The majority of patients pass low-risk almond and hazelnut OFCs. PPVs at the 50th percentile for walnut (2.84 kU/L) and cashew (3.35 kU/L) were lower than those previous studies have suggested.

Basophil activation test shows high accuracy in the diagnosis of peanut and tree nut allergy: The Markers of Nut Allergy Study

BACKGROUND

Peanut and tree nut allergies are the most important causes of anaphylaxis. Co-reactivity to more than one nut is frequent, and co-sensitization in the absence of clinical data is often obtained. Confirmatory oral food challenges (OFCs) are inconsistently performed.

OBJECTIVE

To investigate the utility of the basophil activation test (BAT) in diagnosing peanut and tree nut allergies.

METHODS

The Markers Of Nut Allergy Study (MONAS) prospectively enrolled patients aged 0.5-17 years with confirmed peanut and/or tree nut (almond, cashew, hazelnut, pistachio, walnut) allergy or sensitization from Canadian (n = 150) and Austrian (n = 50) tertiary pediatric centers. BAT using %CD63⁺ basophils (SSClow/CCR3pos) as outcome was performed with whole blood samples stimulated with allergen extracts of each nut (0.001-1000 ng/mL protein). BAT results were assessed against confirmed allergic status in a blinded fashion to develop a generalizable statistical model for comparison to extract and marker allergen-specific IgE.

RESULTS

A mixed effect model integrating BAT results for 10 and 100 ng/mL of peanut and individual tree nut extracts was optimal. The area under the ROC curve (AUROC) was 0.98 for peanut, 0.97 for cashew, 0.92 for hazelnut, 0.95 for pistachio, and 0.97 for walnut. The BAT outperformed sIgE testing for peanut or hazelnut and was comparable for walnut (AUROC 0.95, 0.94, 0.92) in a sub-analysis in sensitized patients undergoing OFC.

CONCLUSIONS

Basophil activation test can predict allergic clinical status to peanut and tree nuts in multi-nut-sensitized children and may reduce the need for high-risk OFCs in patients.

AAAAI Work Group Report: Trends in Oral Food Challenge Practices Among Allergists in the United States

The oral food challenge (OFC) is the criterion standard for diagnosing food allergy, but prior studies indicate many allergists may not be using OFCs for various reasons. To better understand current OFC trends, practices, and barriers, the American Academy of Allergy Asthma and Immunology (AAAAI) Adverse Reactions to Foods Committee subcommittee updated a 19-item survey (previously administered in 2009) and sent it to AAAAI and American College of Allergy, Asthma, and Immunology (ACAAI) membership. There were a total of 546 respondents who represented approximately a 10% response rate. Among the 546 respondents, compared with 2009, significantly more providers offer OFCs (95% vs 84.5%), offer >10 OFCs per month (17% vs 5.6%), obtain informed consent (82.2% vs 53.6%), and performed OFCs in fellowship (71% vs 45%) (all P < .001). Fellowship OFC training was limited, with 56% performing <10 OFCs in fellowship and 29% performing none. Although 94% see patients <12 months of age, 35.5% do not offer OFCs for early peanut introduction. Although 79% dedicate a supervising medical provider (MD, NP, PA) and 86% have a written OFC protocol, only 60% had a standardized reaction treatment protocol and 56% prepared emergency medications before OFC. Compared with 2009, there was significant worsening of perceived barriers to performing OFCs, including time (65.6% vs 55%), space (55.3% vs 27.1%), staffing (59.6% vs 44.3%), experience (16.9% vs 11.5%), and hospital proximity (10.9% vs 7.9%), though reimbursement as a barrier improved (45.9% vs 53.7%) (all P < .01). Compared with 2009, although more providers offer OFCs, multiple perceived barriers to performing OFCs have worsened. Hesitancy to challenge infants and emergency preparedness issues are emerging potential concerns.

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.

Dietary Management of Food Allergy

Worldwide food allergy prevalence is increasing, especially in children. Food allergy management strategies include appropriate avoidance measures and identifying suitable alternatives for a nutritionally sound diet. Individualized dietary intervention begins teaching label reading, which differs among countries or regions. Dietary intervention must result in a nutritionally sound plan including alternatives to support optimal growth and development. Inappropriate or incomplete dietary advice may increase the risk of adverse reactions, growth faltering, and nutrient deficiencies. Evidence indicates input from a registered dietitian improves nutritional outcomes. Nutritional input plays a critical role managing nutritional disorders related to food allergy.

The importance of the 2S albumins for allergenicity and cross-reactivity of peanuts, tree nuts, and sesame seeds

Allergies to peanuts, tree nuts, and sesame seeds are among the most important food-related causes of anaphylaxis. Important clinical questions include: Why is there a variable occurrence of coallergy among these foods and Is this immunologically mediated? The clinical and immunologic data summarized here suggest an immunologic basis for these coallergies that is based on similarities among the 2S albumins. Data from component resolved diagnostics have highlighted the relationship between IgE binding to these allergens and the presence of IgE-mediated food allergy. Furthermore, in vitro and in vivo experiments provide strong evidence that the 2S albumins are the most important allergens in peanuts for inducing an allergic effector response. Although the 2S albumins are diverse, they have a common disulfide-linked core with similar physicochemical properties that make them prime candidates to explain much of the observed coallergy among peanuts, tree nuts, and sesame seeds. The well-established frequency of cashew and pistachio nut coallergy (64%-100%) highlights how the structural similarities among their 2S albumins may account for observed clinical cross-reactivity. A complete understanding of the physicochemical properties of the 2S albumins in peanuts, tree nuts, and sesame seeds will enhance our ability to diagnose, treat, and ultimately prevent these allergies.

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.

Hazelnut Allergy

Background and Objectives: Hazelnuts are frequently involved in IgE-mediated reactions and represent the main culprit of nut allergy in Europe. The clinical presentation varies from mild symptoms limited to the oropharynx [oral allergy syndrome (OAS)], due to the cross-reaction with homologues in pollen allergens and more severe events caused by the primary sensitization to highly stable molecules contained in hazelnuts. The aim of this review is to summarize the most relevant concepts in the field of hazelnut allergy and to provide a practical approach useful in the clinical practice Materials and Methods: References were identified by PubMed searches dating from January 2000 up to November 2020 using the search terms: “component resolved diagnosis” and “Hazelnut allergy. Results: The storage proteins Cor a 9 and Cor a 14 resulted highly specific for primary hazelnut allergy and strongly associated with severe reactions, while the cross reactive Cor a 1, an homolog of the birch Bet v1, were related to OAS. Any cut-off has shown a specificity and sensitivity pattern as high as to replace the oral food challenge (OFC), which still remains the gold standard in the diagnosis of hazelnut allergy. To date there is still no definitive treatment. Hazelnut free-diet and treatment of symptoms with emergency management, including the prescription of auto-injective epinephrine, still represent the main approach. Oral allergen immunotherapy (AIT) appears a promising therapeutic strategy and the definition of individual clinical threshold would be useful for sensitized individuals, caregivers, and physicians to reduce social limitation, anxiety, and better manage food allergy. Conclusions: An accurate diagnostic work-up including clinical history, in vivo and in vitro test including component resolved diagnosis and OFC are essential to confirm the diagnosis, to assess the risk of a severe reaction, and to prescribe an adequate diet and treatment.

Clinical Relevance of Cross-Reactivity in Food Allergy

The diagnosis and management of food allergy is complicated by an abundance of homologous, cross-reactive proteins in edible foods and aeroallergens. This results in patients having allergic sensitization (positive tests) to many biologically related foods. However, many are sensitized to foods without exhibiting clinical reactivity. Although molecular diagnostics have improved our ability to identify clinically relevant cross-reactivity, the optimal approach to patients requires an understanding of the epidemiology of clinically relevant cross-reactivity, as well as the food-specific (degree of homology, protein stability, abundance) and patient-specific factors (immune response, augmentation factors) that determine clinical relevance. Examples of food families with high rates of cross-reactivity include mammalian milks, eggs, fish, and shellfish. Low rates are noted for grains (wheat, barley, rye), and rates of cross-reactivity are variable for most other foods. This review discusses clinically relevant cross-reactivity related to the aforementioned food groups as well as seeds, legumes (including peanut, soy, chickpea, lentil, and others), tree nuts, meats, fruits and vegetables (including the lipid transfer protein syndrome), and latex. The complicating factor of addressing co-allergy, for example, the risks of allergy to both peanut and tree nuts among atopic patients, is also discussed. Considerations for an approach to individual patient care are highlighted.

A remarkable food allergy in children: cashew nut allergy

Objective

The prevalence of cashew nut allergy is increasing. Clinical reaction to cashew nuts may be severe, including anaphylaxis. In this study, we aimed to evaluate the frequency of cashew nut sensitivity in a group of children with food allergy and the clinical features and course of cashew nut allergy.

Material and Methods

A retrospective chart review was performed on 516 children who presented with food allergy at a pediatric allergy department. Individuals sensitized to cashew nuts were examined.

Results

Cashew nut sensitization was detected in 17 (64.7% male; mean age of symptom onset, 14 months) of 516 patients with food allergy. Skin symptoms were the most frequent clinical presentation, followed by gastrointestinal symptoms. Overall, 29.4% of the patients presented with anaphylaxis. All anaphylactic reactions were developed after the first consumption of cashew nuts. Of the cashew nut-sensitized patients, 82.3% were diagnosed with moderate-to-severe atopic dermatitis, and all of them had multiple food allergies. During the follow-up, 90% of the patients who had cashew nut sensitization and co-existing food allergies to cow's milk and/or hen's egg developed tolerance to cow's milk and/or hen's egg, but none of the patients could tolerate cashew nut ingestion.

Conclusion

Cashew nut is a potent allergen, causing severe allergic reactions that persist long term compared with other food allergies. Early onset of moderate-to-severe atopic dermatitis and multiple food allergies are remarkable co-existing conditions in children who have been diagnosed with cashew nut allergy. Pediatricians should be aware of this emerging food allergy.

Model of Walnut Allergy in CC027/GeniUnc Mice Recapitulates Key Features of Human Disease

Tree nut allergies affect 1% of the United States population, are often severe in nature and rarely outgrown. Despite the severity and prevalence, there are no FDA-approved treatments for tree nut allergy. Development of a therapeutic would be expedited by having a mouse model that mimics the human disease. We utilized the CC027/GeniUnc mouse strain, which was previously identified as an orally reactive model of peanut allergy, to develop a model of walnut allergy. Mice were sensitized with walnut and cholera toxin for 4 weeks and subsequently challenged by oral gavage. Blood samples were collected to measure serum IgE. Walnut-sensitized mice produced high levels of walnut-IgE and were cross-sensitized to pecan. Oral challenges with walnut resulted in severe anaphylaxis and accompanying allergic symptoms. Importantly, pecan challenges also led to severe allergic reactions, indicating cross-reactivity to pecan. Overall, this novel mouse model reproduces key characteristics of human walnut allergy, which provides a platform to develop novel therapies and better understand sensitization mechanisms.

Early epitope-specific IgE antibodies are predictive of childhood peanut allergy

BACKGROUND

Peanut allergy is characterized by the development of IgE against peanut antigen.

OBJECTIVE

We sought to evaluate the evolution of epitope-specific (es)IgE and esIgG4 in a prospective cohort of high-risk infants to determine whether antibody profiles can predict peanut allergy after age 4 years.

METHODS

The end point was allergy status at age 4+ years; samples from 293 children were collected at age 3 to 15 months and 2 to 3 and 4+ years. Levels of specific (s)IgE and sIgG4 to peanut and component proteins, and 50 esIgE and esIgG4 were quantified. Changes were analyzed with mixed-effects models. Machine learning algorithms were developed to identify a combination of antigen- and epitope-specific antibodies that using 3- to 15-month or 2- to 3-year samples can predict allergy status at age 4+ years.

RESULTS

At age 4+ years, 38% of children were Tolerant or 14% had Possible, 8% Convincing, 24% Serologic, and 16% Confirmed allergy. At age 3 to 15 months, esIgE profiles were similar among groups, whereas marked increases were evident at age 2 and 4+ years only in Confirmed and Serologic groups. In contrast, peanut sIgE level was significantly lower in the Tolerant group at age 3 to 15 months, increased in Confirmed and Serologic groups but decreased in Convincing and Possibly Allergic groups over time. An algorithm combining esIgEs with peanut sIgE outperformed different clinically relevant IgE cutoffs, predicting allergy status on an "unseen" set of patients with area under the curves of 0.84 at age 3 to 15 months and 0.87 at age 2 to 3 years.

CONCLUSIONS

Early epitope-specific plus peanut-specific IgE is predictive of allergy status at age 4+ years.

Immunoglobulin E-Binding Pattern of Canadian Peanut Allergic Children and Cross-Reactivity with Almond, Hazelnut and Pistachio

Peanut allergic individuals can be both co-sensitized and co-allergic to peanut and tree nuts. At the moment, standard diagnostic approaches do not always allow differentiation between clinically relevant sensitization and nonsignificant cross-reactions, and the responsibility of each allergen remains unclear. The objective of this study was therefore to determine a peanut sensitization profile in a cohort of Canadian peanut allergic children and assess the immunoglobulin E (IgE) molecular cross-reactivity between peanut, almond, hazelnut and pistachio. The specific IgE (sIgE) levels of each patient serum were determined by ImmunoCAP, indirect ELISA and immunoblot to examine their sIgE-binding levels and profiles to peanut proteins. Reciprocal inhibition ELISA and immunoblotting were used to study sIgE cross-reactions between peanut and the selected tree nuts using an adjusted and representative serum pool of the nine allergic patients. The results showed that the prepared peanut and tree nut protein extracts allowed for the detection of the majority of peanut and selected tree nut known allergens. The reciprocal inhibition ELISA experiments showed limited sIgE cross-reactivities between peanut and the studied tree nuts, with peanut being most likely the sensitizing allergen and tree nuts the cross-reactive ones. In the case of hazelnut and pistachio, a coexisting primary sensitization to hazelnut and pistachio was also demonstrated in the serum pool. Reciprocal inhibition immunoblotting further revealed that storage proteins (2S albumin, 7S vicilin and 11S legumin) could possibly account for the observed IgE-cross-reactions between peanut and the studied tree nuts in this cohort of allergic individuals. It also demonstrated the importance of conformational epitopes in the exhibited cross-reactions.

Phenotypical characterization of tree nuts and peanut allergies in east Mediterranean children

INTRODUCTION/OBJECTIVES

The characteristics of tree nuts (TNs) and peanut (PN) allergies vary in different regions of the world. We aim to identify the characteristics of TNs/PN allergies in Turkish children.

PATIENTS AND METHODS

A total of 227 children [4.8 (3.2-6.8) years] with TN and/or PN allergies were included. The phenotypical features of TNs/PN allergic children and the risk factors for multiple TNs/PN allergies were evaluated.

RESULTS

Allergy to TNs/PN developed at a median age of 12.0 (10.0-18.0) months. The most common TNs/PN responsible for food allergies were the hazelnut (63.9%) and the pistachio (54.6%). Of TNs/PN allergic children, 54.2% experienced reactions with at least two types of . Current ages 6-10 years [OR:2.455, 95% CI:1.255-4.852, p=0.009] and family history of atopy [OR:2.156, 95% CI:1.182-3.932, p=0.012] were the risk factors for multiple TNs/PN allergies. Most of the patients with cashew nut and pistachio allergies exhibited co-sensitization and co-allergy to both of these TNs/PN. Although the rarest TNs/PN allergy was seen with almond, the possibility of allergy to other TNs or PN was highly increased in the patients with almond allergy compared to other TNs/PN.

CONCLUSIONS

Children with TNs/PN allergy living in an East Mediterranean region differ from the counterparts living in Western countries by an earlier age of onset of the TNs/PN allergy symptoms, increasing possibility to have multiple TNs/PN allergy at older ages, and different spectrum of TN/PN allergies (hazelnut followed by pistachio/cashew) that all indicate the consumption habits which are important determinants of TN/PN allergy development.

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.

A 5-year retrospective review of children with peanut allergy in the largest paediatric hospital in Singapore

Background

The prevalence of peanut allergy (PA) among children has increased significantly over the past decade. Even though the prevalence of PA in Singapore is considered low, peanut is the top trigger for food-induced anaphylaxis in Singaporean children.

Objective

To describe the demographic characteristics and clinical features of children with PA.

Methods

This is a 5-year retrospective review of children diagnosed with PA based on clinical history coupled with a positive skin prick test to peanut or positive oral food challenge results.

Results

There were 269 patients (53.9% males) with a clinical diagnosis of PA. The median age at first allergic presentation for the PA group was 24 months old, with interquartile range of 13-39 months. The most common form of peanut introduced was roasted peanut. The rate of peanut anaphylaxis was 7.1%. Concomitant tree nut sensitization was found in 32.3% of this cohort, predominantly to cashew nut. Majority of them have a personal history of atopy - 75.8% with eczema, 63.6% with allergic rhinitis, and 19.7% with asthma.

Conclusion

This is the first large review of peanut-allergic children in Singapore. Prospective population-based studies are needed to establish the true prevalence and risk factors associated with the development of this potentially life-threatening condition.

Defining challenge-proven coexistent nut and sesame seed allergy: A prospective multicenter European study

BACKGROUND

Peanut, tree nut, and sesame allergies are responsible for most life-threatening food-induced allergic reactions. Rates of coexistent allergy between these foods have been from mostly retrospective studies that include only a limited number of tree nuts or were not based on oral food challenges.

OBJECTIVE

The Pronuts study is a multicenter European study (London, Geneva, and Valencia) assessing the challenge-proven rate of coexistent peanut, tree nut, and/or sesame seed allergy.

METHODS

Children aged 0 to 16 years with at least 1 confirmed nut or sesame seed allergy underwent sequential diagnostic food challenges to all other nuts and sesame seed.

RESULTS

Overall, the rate of coexistent peanut, tree nut, and sesame seed allergy was 60.7% (n = 74/122; 95% CI, 51.4% to 69.4%). Peanut allergy was more common in London, cashew and pistachio nut allergies were more common in Geneva, and walnut and pecan allergies were more common in Valencia. Strong correlations were found between cashew-pistachio, walnut-pecan, and walnut-pecan-hazelnut-macadamia clusters. Age (>36 months) and center (Valencia > Geneva > London) were associated with an increased odds of multiple nut allergies. By pursuing the diagnostic protocol to demonstrate tolerance to other nuts, participants were able to introduce a median of 9 nuts.

CONCLUSION

We found a higher rate of coexistent nut and sesame seed allergies than previously reported. Performing sequential food challenges was labor intensive and could result in severe allergic reactions; however, it reduced dietary restrictions. Age was a significant predictor of multiple nut allergies, and thus the secondary spread of nut allergies occurred in older children.

A Critical Comparison between Flow-through and Lateral Flow Immunoassay Formats for Visual and Smartphone-Based Multiplex Allergen Detection

(1) Background: The lack of globally standardized allergen labeling legislation necessitates consumer-focused multiplexed testing devices. These should be easy to operate, fast, sensitive and robust. (2) Methods: Herein, we describe the development of three different formats for multiplexed food allergen detection, namely active and passive flow-through assays, and lateral flow immunoassays with different test line configurations. (3) Results: The fastest assay time was 1 min, whereas even the slowest assay was within 10 min. With the passive flow approach, the limits of detection (LOD) of 0.1 and 0.5 ppm for total hazelnut protein (THP) and total peanut protein (TPP) in spiked buffer were reached, or 1 and 5 ppm of THP and TPP spiked into matrix. In comparison, the active flow approach reached LODs of 0.05 ppm for both analytes in buffer and 0.5 and 1 ppm of THP and TPP spiked into matrix. The optimized LFIA configuration reached LODs of 0.1 and 0.5 ppm of THP and TPP spiked into buffer or 0.5 ppm for both analytes spiked into matrix. The optimized LFIA was validated by testing in 20 different blank and spiked matrices. Using device-independent color space for smartphone analysis, two different smartphone models were used for the analysis of optimized assays.

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.

IgE binding to linear epitopes of Ara h 2 in peanut allergic preschool children undergoing oral Immunotherapy

BACKGROUND

For patients with peanut allergy, there are currently no methods to predict who will develop sustained unresponsiveness (SU) after oral immunotherapy (OIT).

OBJECTIVE

Assess IgE binding to peanut (PN), Ara h 2, and specific linear epitopes of Ara h 2 as predictors of the important clinical parameters: eliciting dose threshold and attainment of SU following OIT.

METHODS

Samples and clinical data were collected from children undergoing OIT. PN- and Ara h 2-sIgE were quantified by ImmunoCAP^® . IgE binding to linear peptides of Ara h 2 and Ara h 6 was measured with peptide microarrays.

RESULTS

Values of PN-sIgE correlated with eliciting dose (P = .001) and with a higher likelihood of achieving SU (P < .0001), but these relationships were lost at higher values for PN-sIgE (≥14 kIU for eliciting dose and ≥35 kIU/L for SU). In subjects with PN-sIgE ≥ 14 kIU/L, binding of IgE to epitopes 5 and 6 of Ara h 2 was associated with a lower eliciting dose at baseline challenge (P < .001; P_c  < .02). In subjects with PN-sIgE ≥ 35 kIU/L, a combined model of IgE binding to epitopes 1, 5 and 6 with PN-sIgE was highly predictive of attainment of SU (AUC of 0.86; P = .0067).

CONCLUSION

In young patients with peanut allergy, measurement of PN-sIgE and IgE binding to specific linear epitopes of Ara h 2 in baseline samples may allow stratification of patients regarding sensitivity to challenge and outcome of OIT.