Relationship between specific IgE to egg components and natural history of egg allergy in Danish children

Systematic review and meta-analyses on the accuracy of diagnostic tests for IgE-mediated food allergy

The European Academy of Allergy and Clinical Immunology (EAACI) is updating the Guidelines on Food Allergy Diagnosis. We aimed to undertake a systematic review of the literature with meta-analyses to assess the accuracy of diagnostic tests for IgE-mediated food allergy. We searched three databases (Cochrane CENTRAL (Trials), MEDLINE (OVID) and Embase (OVID)) for diagnostic test accuracy studies published between 1 October 2012 and 30 June 2021 according to a previously published protocol (CRD42021259186). We independently screened abstracts, extracted data from full texts and assessed risk of bias with QUADRAS 2 tool in duplicate. Meta-analyses were undertaken for food-test combinations for which three or more studies were available. A total of 149 studies comprising 24,489 patients met the inclusion criteria and they were generally heterogeneous. 60.4% of studies were in children ≤12 years of age, 54.3% were undertaken in Europe, ≥95% were conducted in a specialized paediatric or allergy clinical setting and all included oral food challenge in at least a percentage of enrolled patients, in 21.5% double-blind placebo-controlled food challenges. Skin prick test (SPT) with fresh cow's milk and raw egg had high sensitivity (90% and 94%) for milk and cooked egg allergies. Specific IgE (sIgE) to individual components had high specificity: Ara h 2-sIgE had 92%, Cor a 14-sIgE 95%, Ana o 3-sIgE 94%, casein-sIgE 93%, ovomucoid-sIgE 92/91% for the diagnosis of peanut, hazelnut, cashew, cow's milk and raw/cooked egg allergies, respectively. The basophil activation test (BAT) was highly specific for the diagnosis of peanut (90%) and sesame (93%) allergies. In conclusion, SPT and specific IgE to extracts had high sensitivity whereas specific IgE to components and BAT had high specificity to support the diagnosis of individual food allergies.

Introduction of Egg White and Yolk to Infant Diets and Early Childhood Atopic Dermatitis

This study investigated whether the introduction of allergenic foods in infancy is associated with atopic dermatitis (AD) in early childhood. Information regarding parental allergic histories, the introduction of six possible allergenic foods (fruits, egg white, egg yolk, fish, shellfish, and peanuts), and physician-diagnosed AD was obtained using age-specific questionnaires (0-2 years). Immunoglobulin E, specific to 20 food allergens, was also quantified at 12 months of age. Logistic regression analyses were used to determine the association between individual food introduction and the outcomes of food sensitization and AD. We found AD development by 2 years of age was significantly related to a parental history of allergy (adjusted odds ratio (aOR) = 1.29) and not being introduced to egg white and yolk during infancy (aORs = 2.27 and 1.97, respectively). Stratified analyses revealed that the introduction of both egg white and yolk was negatively associated with AD by 2 years of age, especially for those children where both parents had allergic diseases (aOR = 0.10). In summary, the introduction of egg white and yolk to an infant's diet may be a modifiable factor in reducing the risk of physician-diagnosed AD by 2 years of age, which may be particularly important for infants where both parents have allergies.

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.

Risk factors for failing a repeat oral food challenge in preschool children with hen's egg allergy

BACKGROUND

Children with hen's egg (HE) allergy and a positive initial oral food challenge (OFC) require rechallenge to assess for tolerance. However, the risk factors for a positive repeat OFC remain unclear.

METHODS

We retrospectively analyzed data from 243 preschool children who failed an initial OFC with half a heated HE and repeated the same OFC after 6-24 months. Logistic regression models were used to determine risk factors for a positive repeat OFC, including factors that were ascertainable immediately after the initial OFC and at the repeat OFC as variables.

RESULTS

The median age, egg white-, and ovomucoid-specific IgE (sIgE) were 3.5 years, 12.7, and 7.2 kU_A /L, respectively. The median interval between OFCs was 12.4 months and repeat OFCs were positive in 132 (54%) patients. One multivariate analysis model indicated that risk factors for a positive repeat OFC included cumulative dose (adjusted odds ratio [aOR]:0.58), anaphylaxis (aOR: 3.09), total serum IgE (aOR: 0.41), ovomucoid-sIgE (aOR: 3.21), and age (aOR: 1.68) at the initial OFC. Another model indicated that the risk factors were cumulative dose (aOR: 0.59) and anaphylaxis (aOR: 3.41) at initial OFC and total serum IgE (aOR: 0.36), ovomucoid-sIgE (aOR: 4.93), and age (aOR: 1.30) at repeat OFC.

CONCLUSION

Low threshold dose and severe symptoms at initial OFC, and low total serum IgE, high ovomucoid-sIgE and higher age at initial and repeat OFCs are risk factors for the persistence of HE allergy and they may be useful when deciding the rechallenge interval for heated HE in preschool children.

Phenotyping of immediate-type food allergies based on 10 years of research: A latent class analysis

BACKGROUND

Food allergy is a disease with a diverse and variable natural history, and some patients may react to two or more food antigens. This study aimed to classify and characterize the long-term prognosis of infantile-onset, immediate-type food allergies, focusing on three major antigens in Japan: egg, milk, and wheat.

METHODS

All children who visited our hospital with food allergies, including suspected cases, were prospectively registered in our medical database. Among the children in this database, subjects registered by the age of 1 year with immediate-type symptoms or sensitization to the above three antigens were included. The course of the subjects up to the age of 6 years was analyzed. Cox regression analysis and repeated-measures latent class analysis (LCA) were performed to reveal risk factors and tolerance patterns for food allergies.

RESULTS

We included 915 patients with immediate-type food allergy symptoms and 276 sensitized asymptomatic patients in this study. The number of patients with immediate-type symptoms to egg, milk, and wheat was 609, 443, and 235, respectively. The number of patients with multiple food allergies was 302. The proportion of patients with tolerance to egg, milk, and wheat at 6 years of age was 74%, 69%, and 75%, respectively. LCA revealed 7 classes of prognosis for food allergies. The largest class was transient egg allergy alone (19.6%), and there were severe cases of multiple food allergies (6.5%).

CONCLUSIONS

This study demonstrated the prognosis of food allergy classes in Japan, including multiple food allergies, with 7 classes with its own characteristics.

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

INTRODUCTION

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

AREAS COVERED

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

EXPERT OPINION

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

Prognosis of food-induced anaphylaxis in children: A single-center real-life study

Background: Food allergies are known to resolve over time, but there is little information on the natural history of food-induced anaphylaxis (FIA). Objective: This study aimed to evaluate the natural history of FIA in children and determine the factors that affect prognosis. Methods: Children with FIA who were followed up for at least 3 years, between 2010 and 2020, were included. Patients' families were contacted by telephone to question their child's tolerance status and invite them for reevaluation if uncertain. The patients were grouped as tolerant or persistent according to parent reports or reevaluation results. Logistic regression analysis was performed to determine the factors that affected persistence. Results: The study included 185 patients (62.2% boys) with 243 anaphylactic reactions to various foods. Fifty-eight patients (31%) gained tolerance within a 3-year follow-up period. Tolerance rates were higher in patients with FIA to milk (40%) and egg (43.9%) compared with to tree nuts (18.8%), legumes (5.6%), and/or seafood (11.1%) (p < 0.001). In a multivariate analysis, risk factors for persistent FIA were multiple food anaphylaxis (odds ratio [OR] 3.755 [95% confidence interval {CI}, 1.134-12.431]; p = 0.030), total IgE > 100 kU/L (OR 5.786 [95% CI, 2.065-16.207]; p = 0.001), and skin-prick test wheal size > 10 mm (OR 4.569 [95% CI, 1.395-14.964]; p = 0 .012) at presentation. Conclusion: Approximately a third of the patients with FIA developed tolerance within 3 years. Clinicians should remember that children with food allergies, even anaphylaxis, may develop tolerance over time. Regular follow up and reevaluation of tolerance status are necessary to avoid unnecessary elimination.

BSACI 2021 guideline for the management of egg allergy

This guideline advises on the management of patients with egg allergy. Most commonly egg allergy presents in infancy, with a prevalence of approximately 2% in children and 0.1% in adults. A clear clinical history will confirm the diagnosis in most cases. Investigation by measuring egg-specific IgE (by skin prick testing or specific IgE assay) is useful in moderate-severe cases or where there is diagnostic uncertainty. Following an acute allergic reaction, egg avoidance advice should be provided. Egg allergy usually resolves, and reintroduction can be achieved at home if reactions have been mild and there is no asthma. Patients with a history of severe reactions or asthma should have reintroduction guided by a specialist. All children with egg allergy should receive the MMR vaccine. Most adults and children with egg allergy can receive the influenza vaccine in primary care, unless they have had anaphylaxis to egg requiring intensive care support. Yellow Fever vaccines should only be considered in egg-allergic patients under the guidance of an allergy specialist. This guideline was prepared by the Standards of Care Committee (SOCC) of the British Society for Allergy and Clinical Immunology (BSACI) and is intended for allergists and others with a special interest in allergy. The recommendations are evidence based. Where evidence was lacking, consensus was reached by the panel of specialists on the committee. The document encompasses epidemiology, risk factors, diagnosis, treatment, prognosis and co-morbid associations.

Component-Resolved Diagnostic Study of Egg Allergy in Northern Chinese Children

BACKGROUND

Egg component-specific IgE can be useful to evaluate and diagnose egg allergy, but their prevalence and clinical significance remain unclear in the local population. Previous studies have led to contradictory results regarding the value of specific IgG and specific IgG4 in sensitization.

OBJECTIVE

We aimed to determine the level of specific IgE, IgG, and IgG4 antibodies to the major egg allergens in egg-allergic children.

METHODS

Children from 6 months to 10 years of age were recruited. Egg allergy was confirmed by either a strong clinical history or an increased egg white-sIgE level. Other allergies were diagnosed by reactivity to other allergens but without egg-related symptoms and history. The serum sIgE, sIgG, and sIgG4 levels to major egg allergenic components (Gal d 1, Gal d 2, Gal d 3, Gal d 4, and Gal d 5), sIgE level to egg white, and tIgE level were determined by light-initiated chemiluminescent assay (LICA), ELISA, or ImmunoCAP.

RESULTS

Egg-allergic children had significantly higher levels of sIgE, sIgG, and sIgG4 to egg components than nonallergic children. Gal d 2 was the predominant allergen, and Gal d 2 sIgE level correlated with the egg white-sIgE level. Ratios of sIgE/sIgG4 to egg components were highest before 1 year of age and dropped gradually in the first decade of life.

CONCLUSION

Patterns of sIgE to egg components could distinguish different forms of egg allergy. Ratios of sIgE/sIgG4 could be useful in predicting tolerance in egg-sensitive subjects, but this needs further evaluation and investigation using more accurate models.

Gal d 1-specific IgE predicts allergy to heated egg in Finnish children

BACKGROUND

Allergen-specific IgE levels can be useful in predicting outcomes of oral food challenges, but optimal cutoff levels vary in different populations. The aim was to determine cutoff values for egg white- and Gal d 1-, Gal d 2-, Gal d 3-, and Gal d 4-specific IgE (sIgE) predicting positive oral heated egg challenges in 185 Finnish children and adolescents.

METHODS

A total of 185 egg-sensitized patients (age: 1-19 years, median: 6.3, mean: 7.0 years) with suspected egg allergy underwent double-blind, placebo-controlled (n = 78), or open (n = 107) oral food challenges with heated egg white. Specific IgE levels to egg white, Gal d 1 (ovomucoid), Gal d 2 (ovalbumin), Gal d 3 (conalbumin), and Gal d 4 (lysozyme) were measured by ImmunoCAP and compared with challenge outcomes.

RESULTS

Of the 185 challenges, 124 (67%) were positive. Gal d 1 sIgE levels were significantly higher in the challenge-positive (median 13.5 kU/L, mean 33.2 kU/L) than in the challenge-negative group (median 0.2 kU/L, mean 1.2 kU/L), P < 0.0001. The diagnostic capacity of sIgE to egg white and Gal d 2, 3, and 4 was clearly weaker. In ROC analysis, the AUC for egg white was 0.86, Gal d 2 0.84, Gal d 3 0.79, and Gal d 4 0.77. Sensitization to Gal d 1 with a cutoff of value of >3.7 kU/L predicted a positive challenge with a specificity of 95% and sensitivity of 78%. The likelihood ratio was 15.9. In ROC analysis, the area under the curve was 0.94 (95% CI, 0.91-0.97). With a cutoff value of >14 kU/L, all challenges were positive, and with a cutoff of <0.9 kU/L, 95% of the challenges were negative. In the children aged 1-5 years (n = 88), the cutoff for Gal d 1 was >3.8 kU/L, and in the children above 6 years of age (n = 97), it was >3.5 kU/L.

CONCLUSION

Gal d 1-specific IgE is useful in distinguishing egg-sensitized patients with clinically reactive egg allergy from those tolerant of heated egg. The optimal cutoff point in a Finnish population of 185 children and adolescents was 3.7 kU/L with no significant difference between the younger and older age groups.

Cow's milk allergic children-Can component-resolved diagnostics predict duration and severity?

BACKGROUND

Cow's milk allergy (CMA) affects 2% of all children. This study investigatescomponent-resolved diagnostics(CRD) to cow's milk proteins in children suspected of CMA, by correlating the level of CRD with outcome of the oral challenge. Furthermore, we evaluate the ability of serial CRD measurements to distinguish children with persistent CMA from children developing tolerance.

METHODS

We included data from 78 children referred to the Allergy Centre during a 13-year period. Results from oral food challenges including threshold, severity, and sensitization data (IgE antibodies to whole milk protein, IgE components toward milk and skin prick test (SPT)) were collected. The milk allergic children were re-evaluated with sensitization data and rechallenges regularly.

RESULTS

Thirty-nine children had negative first challenges, and 39 had positive first challenges. The positive group was rechallenged and separated into 3 groups depending on time to remission. At inclusion, children with persistent CMA had significantly larger size of SPT and higher levels of s-IgE to milk and CRD compared to the other groups. SPT wheal size was significantly larger in children with persistent CMA compared to children outgrowing CMA. Furthermore, a correlation between s-IgE level to cow's milk and casein and the severity of the allergic reaction elicited by food challenges was found.

CONCLUSION

Oral food challenge cannot be replaced by s-IgE to whole milk protein or milk components nor SPT in the diagnosis of CMA; however, high levels of milk components and s-IgE to milk increase the risk of a long-lasting or persisting CMA.

Food allergy and atopic dermatitis: Prediction, progression, and prevention

The rising burden of allergic diseases in childhood requires a compelling need to identify individuals at risk for atopy very early in life or even predict the onset of food allergy and atopic dermatitis since pregnancy. The development and clinical phenotypes of atopic diseases in childhood depend on a complex interaction between genetic and environmental factors, such as allergen exposure, air pollution, and infections. Preventive strategies may include avoidance measures, diet supplements, and early complementary food introduction. Overall, the management of allergic diseases has been improving to date toward a patient's tailored approach. This review will cover the current understanding of risk factors, prediction, and management of food allergy and atopic dermatitis in childhood and discuss how these may contribute to the modification of the natural history of food allergy and atopic dermatitis.