Heated egg yolk challenge predicts the natural course of hen's egg allergy: a retrospective study

Management of food allergy based on oral food challenge

PURPOSE OF REVIEW

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

RECENT FINDINGS

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

SUMMARY

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

Research progress on the allergic mechanism, molecular properties, and immune cross-reactivity of the egg allergen Gal d 5

Eggs and their products are commonly consumed in food products worldwide, and in addition to dietary consumption, egg components are widely used in the food industry for their antimicrobial, cooking, and other functional properties. Globally, eggs are the second most common allergenic food after milk. However, current research on egg allergy primarily focuses on egg white allergens, while research on egg yolk allergens is not comprehensive enough. Therefore, summarizing and analyzing the important allergen α-livetin in egg yolk is significant in elucidating the mechanism of egg allergy and exploring effective desensitization methods. This paper discusses the incidence, underlying mechanism, and clinical symptoms of egg allergy. This article provides a comprehensive summary and analysis of the current research status concerning the molecular structural properties, epitopes, and immune cross-reactivity of the egg yolk allergen, Gal d 5. Additionally, it examines the effects of various processing methods on egg allergens. The article also offers suggestions and outlines potential future research directions and ideas in this field.

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.

Food allergen ladders: A need for standardization

INTRODUCTION

The process of gradually reintroducing food allergens into an individual's diet is referred to as food allergen "ladders". There remain many questions regarding the foods chosen, structure and composition of the ladder, and medical and safety considerations. The COVID-19 pandemic has propelled us into an era where medicine is increasingly practiced via online platforms, highlighting the need for standardized food allergen ladder approaches for successful and safe introduction of food allergens.

METHODS

We performed a search of currently published food allergen ladders and obtained published information and clinical expertise to summarize current knowledge and suggest future standardized approaches for using food allergen ladders.

RESULTS

There are currently a limited number of published milk, egg, wheat, and soy ladders. We suggest the following points should be considered when developing food ladders: (1) Food allergen: dose, time, and temperature of heating of the food allergen, simplicity of the ladder and recipes, the possible role of the wheat matrix, and testing for allergenic protein levels to standardize doses; (2) Nutritional factors: health and nutritional value of the foods in the ladder, taste, texture, and cultural appropriateness of foods should be considered; and (3) Medical aspects: consideration of which patients are safe to undergo ladders outside of the clinical setting, other safety aspects and risk factors for severe reactions, number of days suggested per steps, and availability and provision of rescue medication. Written instructions and recipes should be provided to families who wish to use food allergen ladders.

DISCUSSION

Food allergen ladders used for gradual reintroduction of food allergens into a food allergic individual's diet are increasingly being used internationally. Standardization regarding the foods included in the ladder and medical considerations are required to practice patient-centered care, best assist patients and families, and ensure safety.

Safe egg yolk consumption after a negative result for low-dose egg oral food challenge

BACKGROUND

Hen's egg is one of the most common allergens causing infantile food allergy. Consuming heated egg yolk slightly contaminated with egg white (EY with scEW) improves diet quality. Most children with egg allergies can safely consume 1/25 of a heated whole egg (low-dose egg). Although low-dose egg has similar antigenicity to EY with scEW, clinical reproducibility is unknown. We aimed to examine the safety of EY with scEW consumption after a negative result of low-dose egg oral food challenge (OFC).

METHODS

In this prospective study, children aged <18 years with a history of immediate reaction to eggs were enrolled. We advised children and guardians to consume EY with scEW after a negative result of low-dose egg OFC and to record symptoms, if any.

RESULTS

We evaluated 276 children with negative results for low-dose egg OFC who had previously shown reactivity to eggs. Their median age was 1.2 years. Boys accounted for 188 (68%) of the children. The median egg white-specific immunoglobulin E level was 11.7 kU_A /L. At home, six children experienced mild symptoms. Skin symptoms were the most common. Among the six children, five were confirmed to continue the consumption of EY with scEW and one developed mild respiratory symptoms and continued to avoid eating eggs.

CONCLUSION

Although a few children with egg allergies experience mild symptoms, most of them can ultimately consume EY with scEW. Consumption of EY with scEW after low-dose egg OFC seems safe and may improve their quality of life by making egg yolk products available.

Japanese guidelines for food allergy 2020

Five years have passed since the Japanese Pediatric Guideline for Food Allergy (JPGFA) was first revised in 2011 from its original version. As many scientific papers related to food allergy have been published during the last 5 years, the second major revision of the JPGFA was carried out in 2016. In this guideline, food allergies are generally classified into four clinical types: (1) neonatal and infantile gastrointestinal allergy, (2) infantile atopic dermatitis associated with food allergy, (3) immediate-type of food allergy (urticaria, anaphylaxis, etc.), and (4) special forms of immediate-type of food allergy such as food-dependent exercise-induced anaphylaxis and oral allergy syndrome (OAS). Much of this guideline covers the immediate-type of food allergy that is seen during childhood to adolescence. Infantile atopic dermatitis associated with food allergy type is especially important as the onset of most food allergies occurs during infancy. We have discussed the neonatal and infantile gastrointestinal allergy and special forms of immediate type food allergy types separately. Diagnostic procedures are highlighted, such as probability curves and component-resolved diagnosis, including the recent advancement utilizing antigen-specific IgE. The oral food challenge using a stepwise approach is recommended to avoid complete elimination of causative foods. Although oral immunotherapy (OIT) has not been approved as a routine treatment by nationwide insurance, we included a chapter for OIT, focusing on efficacy and problems. Prevention of food allergy is currently the focus of interest, and many changes were made based on recent evidence. Finally, the contraindication between adrenaline and antipsychotic drugs in Japan was discussed among related medical societies, and we reached an agreement that the use of adrenaline can be allowed based on the physician's discretion. In conclusion, this guideline encourages physicians to follow the principle to let patients consume causative foods in any way and as early as possible.

Improvement of the sensitivity of the detection of Gal d 6-specific IgE via biotinylation in vivo

INTRODUCTION AND OBJECTIVES

This study aimed to compare the effects of different biotinylation methods on the performance characteristics of allergen-specific IgE detection.

MATERIALS AND METHODS

The Gal d 6 gene was cloned into the pAN6/pAC6 vector, resulting in rGal d 6-Bio/Bio-rGal d 6 vector. The fusion protein was expressed in Escherichia coli AVB101 and simultaneously biotinylated in a site-specific manner. The Gal d 6 gene was amplified via PCR and cloned into the pET-28a vector and transformed into E. coli BL21 and purified via Ni-NTA, followed by chemical biotinylation using Sulfo-NHS-LC-Biotin. Twenty-eight patients allergic to hen's egg white were examined for sensitization against egg yolk. An antigen-capture enzyme-linked immunosorbent assay (AC-ELISA) was developed to detect allergen-specific IgE.

RESULTS

rGal d 6, Bio-rGal d 6, and rGal d 6 were prepared using different biotin binding modes to detect allergen-specific IgE. rGal d 6-Bio (Kd=0.6154) and Bio-rGal d 6 (Kd=0.6698) had a markedly better detection performance than rGal d 6 (Kd=28.93), and the rGal d 6-Bio had a better detection performance in small-volume serum samples.

CONCLUSIONS

rGal d 6-Bio improved the sensitivity for the detection of allergen-specific IgE.

Hyperresponsiveness to Boiled Egg Yolk in Early Life Leads to Prolonged Egg Allergy

Hen's egg is the most common allergen in IgE-mediated food allergy among children in Japan. Although the majority of patients with egg allergy can eat heated egg yolk safely because of its low allergenicity, severely allergic patients show an immediate-type reaction to heated egg yolk. We hypothesized that patients with hyperresponsiveness to boiled egg yolk may have difficulty in acquiring tolerance to egg. The purpose of this study was to examine the prognosis of patients with hyperresponsiveness to boiled egg yolk. Data from 121 patients with egg allergy who underwent oral food challenge (OFC) with boiled egg yolk between January 2012 and December 2013 were analyzed retrospectively. The proportion of patients who could consume heated whole egg 3 years after OFC was 15.4% in the OFC-positive group and 75.8% in the OFC-negative group. Hyperresponsiveness to boiled egg yolk in early life might lead to prolonged egg allergy in children. This finding might aid in the selection of an appropriate population requiring practical immunotherapy.

Immunological Comparison of Native and Recombinant Hen's Egg Yolk Allergen, Chicken Serum Albumin (Gal d 5), Produced in Kluveromyces lactis

Chicken serum albumin (CSA) is a hen’s egg yolk allergen causing IgE-mediated allergy. The objective of this study was to produce a recombinant version of CSA and compare its IgE reactivity to natural CSA (nCSA). CSA was cloned and expressed as a soluble fraction in the yeast Kluyveromyces lactis (K. lactis) protein expression system. The gene encoding CSA was amplified with a C-terminal hemagglutinin epitope tag by polymerase chain reaction (PCR) and cloned into the pKLAC2 expression vector prior to transforming into K. lactis. Recombinant CSA (rCSA) was purified by immunoprecipitation. Twenty-one patients allergic to hen’s egg white were examined for sensitisation against nCSA. 38% of patients were found to be sensitised to CSA based on Western immunoassay. Immunoglobulin E (IgE) binding capacity of rCSA and nCSA was analysed by ELISA using sera from patients sensitised to CSA. Levels of IgE-binding were similar for both the recombinant and the natural CSA, indicating the existence of similar epitopes. rCSA produced in this study is a potential candidate to be used in component-resolved diagnosis (CRD) of egg yolk allergy. The usefulness of rCSA in CRD of egg yolk allergy warrants further characterisation using sera from patients with allergy to hen’s egg yolk in future studies.

Novel immunotherapy and treatment modality for severe food allergies

PURPOSE OF REVIEW

In recent years, many studies on oral immunotherapy (OIT) have been conducted; however, few have focused on severe food allergies. The purpose of this review was to assess the efficacy and safety of oral immunotherapies for patients with severe food allergy.

RECENT FINDINGS

We reviewed multiple immunotherapy reports published within a few years or reports focusing on severe food allergies. We also investigated recent studies on OIT and novel food allergy management.

SUMMARY

Immunotherapies targeting low-dose antigen exposure and oral food challenges using low-dose target volumes may be safer than conventional OIT. It is necessary to consider which immunotherapy regimen is appropriate based on allergy severity of the patient.

Clinical aspects of oral immunotherapy for the treatment of allergies

Studies on oral immunotherapy (OIT) have been increasing worldwide. Nevertheless, some concerns exist with this treatment. The rate of long-term sustained unresponsiveness is quite low; moreover, the desensitization or sustained unresponsiveness does not equate to tolerance. Furthermore, adverse reactions are frequent. Therefore, safe and feasible methods for long-term therapies are needed. Novel therapies such as low-dose OIT, hypoallergenic products, and OIT in combination with omalizumab are reported as effective for inducing sustained unresponsiveness and may lead to fewer adverse reactions than standard OIT. Increased safety will contribute to feasibility of OIT. Currently, oral food challenge (OFC) with the low target dose has been reported. We may reduce the need for OIT by implementing low-dose OFC. More effective, safe, and feasible OIT strategies are needed.

Japanese guidelines for food allergy 2017

Five years have passed since the Japanese Pediatric Guideline for Food Allergy (JPGFA) was first revised in 2011 from its original version. As many scientific papers related to food allergy have been published during the last 5 years, the second major revision of the JPGFA was carried out in 2016. In this guideline, food allergies are generally classified into four clinical types: (1) neonatal and infantile gastrointestinal allergy, (2) infantile atopic dermatitis associated with food allergy, (3) immediate-type of food allergy (urticaria, anaphylaxis, etc.), and (4) special forms of immediate-type of food allergy such as food-dependent exercise-induced anaphylaxis and oral allergy syndrome (OAS). Much of this guideline covers the immediate-type of food allergy that is seen during childhood to adolescence. Infantile atopic dermatitis associated with food allergy type is especially important as the onset of most food allergies occurs during infancy. We have discussed the neonatal and infantile gastrointestinal allergy and special forms of immediate type food allergy types separately. Diagnostic procedures are highlighted, such as probability curves and component-resolved diagnosis, including the recent advancement utilizing antigen-specific IgE. The oral food challenge using a stepwise approach is recommended to avoid complete elimination of causative foods. Although oral immunotherapy (OIT) has not been approved as a routine treatment by nationwide insurance, we included a chapter for OIT, focusing on efficacy and problems. Prevention of food allergy is currently the focus of interest, and many changes were made based on recent evidence. Finally, the contraindication between adrenaline and antipsychotic drugs in Japan was discussed among related medical societies, and we reached an agreement that the use of adrenaline can be allowed based on the physician's discretion. In conclusion, this guideline encourages physicians to follow the principle to let patients consume causative foods in any way and as early as possible.