Egg allergy: are all childhood food allergies the same?

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.

Effect of enzyme immobilization and in vitro digestion on the immune-reactivity and sequence of IgE epitopes in egg white proteins

Immune-reactivity reduction of egg white proteins by free and immobilized enzymes and determination of degraded IgE epitopes.

Allergen immunotherapy for food allergy from the Asian perspective: key challenges and opportunities

Introduction: Prevalence of food allergy is rising in different regions of the world. Asia has not been spared from this epidemic, but epidemiological data have revealed a different pattern of food allergens in this continent. Allergen-specific immunotherapy (AIT) for food allergy, which has been revolutionary as the main focus of research in recent years, needs to be adapted for the different populations in Asia. Areas covered: Recent evidence shows increasing popularity and superiority of AIT over strict food avoidance as the cornerstone of food allergy management. Asia is a distinctive continent with specific food allergy triggers, in particular, seafood, and wheat. Peanut, on the contrary, is not a common food allergen in most parts of Asia. The common Asian food allergens, as well as the rapidly developing food-specific AIT in this region will be covered in this article. Expert commentary: Evidence on oral immunotherapy for wheat allergy and preclinical data on shellfish AIT are promising. Further work should be done on resolving cross-sensitization between environmental allergens with wheat and shellfish allergens, and a modified AIT approach to enhance the safety and effectiveness of food-specific immunotherapy.

Enzymatic characterisation of the immobilised Alcalase to hydrolyse egg white protein for potential allergenicity reduction

BACKGROUND

This study examined technique characteristics of the immobilised Alcalase to hydrolyse egg white protein for potential allergenicity reduction. Alcalase was immobilised covalently on carboxyl-functionalised magnetic beads by carbodiimide activation. The technique characteristics of the immobilised Alcalase were investigated, followed by determining the degrees of hydrolysis (DH), immunoglobulin G (IgG) binding, and IgE binding of the digested egg white protein by immobilised Alcalase.

RESULTS

Enzymatic activity, enzyme loading, and immobilisation yield of the prepared immobilised Alcalase were 20.55 U mg^-1 , 925 mg g^-1 , and 45%, respectively. Immobilised Alcalase showed maximum activity at pH 8.0 and 60 °C. Compared with free Alcalase, immobilised Alcalase exhibited better thermal and storage stability. Moreover, immobilised Alcalase can be reused 10 times and still maintained 55% of its initial activity. Partial hydrolysis of egg white protein by immobilised Alcalase can effectively reduce IgG and IgE binding of the hydrolysates.

CONCLUSION

This study indicates that the immobilised Alcalase can be used to hydrolyse continuously egg white protein for potential allergenicity reduction. © 2016 Society of Chemical Industry.

Screening for hen's egg and chicken meat specific IgE antibodies in Saudi patients with allergic disorders

BACKGROUND

Allergy to hen's egg and meat contributes significantly to the manifestations of food allergy all over the world.

OBJECTIVES

This study was performed to assess the presence of hen's egg and meat specific IgE antibodies among patients investigated for various allergic disorders.

METHODS

This is a retrospective study performed at King Khalid University Hosptial, Riyadh. Data from 421 patients with allergic disorders screened for food specific IgE antibodies between January 2009 and March 2011 were analyzed. Sixty (14.25%) patients including 42 males and 18 females with the mean age (sd) of 7.5 (7.4) years were found to have specific IgE antibodies against hen's egg and chicken meat. There were 56 (93.3%) children and 4 (6.7%) adult patients. Specific IgE antibodies were measured by radioallergosorbent test (RAST) using Pharmacia ImmunoCAP 250 analyzer.

RESULTS

Atopic dermatitis was the most common (55%) clinical condition. Out of the total 60 patients harboring hen's egg and chicken meat specific IgE antibodies high levels of egg white, yolk and chicken meat specific IgEs were detected in 58 (96.6%), 37 (61.6%) and 6 (10%) patients respectively. Both the egg white and yolk antibodies coexisted in 35 (58.3%) patients.

CONCLUSION

Sensitization against hen's egg was higher compared to the chicken meat. Egg white sensitization higher than the egg yolk particularly in Saudi children with food related allergic disorders.

The study of egg allergy in children with atopic dermatitis

CONTEXT

: Food allergy plays a significant pathogenic role among children with atopic dermatitis (AD).

OBJECTIVE

: The aims of this study were to evaluate allergy to egg in these children and determine the egg specific immunoglobulin E (IgE) cutoff point.

DESIGN AND SETTING

: It was a cross-sectional study that took place at Immunology, Asthma and Allergy Research Institute from 2005 to 2007.

METHODS

: Children younger than 14 years old with AD entered the study. Careful medical histories were taken and skin prick and Immuno-CAP tests with the most commonly offending foods (cow's milk, egg, wheat, peanut, and soy) were performed. Children with a clear, positive history of food allergy and a positive IgE-mediated test or those with positive responses to both IgE-mediated tests were determined to have food allergies. The egg-specific IgE level cutoff point was determined.

RESULTS

: A hundred patients entered the study (from 2 months to 12 years old). They were divided into 3 age groups: first <2 years, second from 2 to <6 years, and third from 6 to 14 years. The most common food allergens were egg (39.22%) in the first, cow's milk (35.13%) and egg (32.43%) in the second, and peanut (25%) and egg (16.67%) in the third group. The egg-specific IgE cutoff point value was 0.62 kUA/L (kilounits of allergen-specific IgE per liter). The positive predictive value was 95%.

CONCLUSION

: Prevalence of egg allergy is highly significant in patients with AD.To use egg-specific IgE level cutoff point, the patient population under study must be considered.

Ovomucoid (Gal d 1) specific IgE detected by microarray system predict tolerability to boiled hen's egg and an increased risk to progress to multiple environmental allergen sensitisation

BACKGROUND

Egg allergy is a very common finding in early childhood. Detecting hen's egg (HE) allergy outgrowing and reintroduction of food containing egg is a task for the allergist.

OBJECTIVE

We sought to evaluate the suitability of boiled egg food challenge compared with IgE to allergenic molecules from HE white using a microarray system.

METHOD

Sixty-eight children referring to our centre by the family paediatricians for a suspected egg allergy were enrolled. Patients underwent double-blind, placebo-controlled food challenge with boiled and raw eggs. Challenge outcomes were compared with skin tests performed using egg white and yolk commercial extracts, to prick-prick test with boiled and raw egg white and yolk, total IgE, egg white specific IgE detected using ImmunoCAP and IgE to egg allergens available on the immunosolid phase allergen chip (ISAC) 103 microarray.

RESULT

Nineteen subjects (28%) were reactive to both raw and boiled egg, 14 (20.5%) to raw egg only and 35 (51.4%) tolerated both boiled and raw egg. Efficiency analysis was carried out using both raw and boiled egg challenges as gold standard. Forty four of 47 Gal d 1 negative patients tolerated boiled egg (94%). Conversely, 20 of 21 Gal d 1 positive patients reacted to raw egg (95%). None of the other tests was able to discriminate patients' response to HE challenge. Furthermore, Gal d 1 positivity seems to lead to broader environmental allergen IgE sensitization.

CONCLUSION AND CLINICAL RELEVANCE

The Gal d 1 IgE reactivity appears to be a very good predictor of HE clinical allergy. Gal d 1 positive children have a high frequency of HE allergy, whereas Gal d 1 negative children have a high frequency of tolerance to boiled egg. Multiple specific IgE detection by means of ISAC improves the diagnostic approach in HE allergic children, disclosing other food and inhalant allergic sensitizations, anyhow requiring a comprehensive clinical evaluation.

Is aboriginal food less allergenic? Comparing IgE-reactivity of eggs from modern and ancient chicken breeds in a cohort of allergic children

BACKGROUND

Hen's egg allergy ranks among the most frequent primary food allergies in children. We aimed to investigate sensitization profiles of egg allergic patients and compare in vitro IgE reactivities of eggs from ancient chicken breeds (Araucana and Maran) with those from conventional laying hen hybrids.

METHODOLOGY

Egg allergic children (n = 25) were subjected to skin prick test, double blind placebo controlled food challenge, and sensitization profiles to Gal d 1-5 were determined by allergen microarray. IgE binding and biological activity of eggs from different chicken breeds were investigated by immunoblot, ELISA, and mediator release assays.

PRINCIPAL FINDINGS

We found that Gal d 1 and Gal d 2 are generally major egg allergens, whereas Gal d 3-5 displayed high sensitization prevalence only in patients reacting to both, egg white and yolk. It seems that the onset of egg allergy is mediated by egg white allergens expanding to yolk sensitization in later stages of disease. Of note, egg white/yolk weight ratios were reduced in eggs from Auraucana and Maran chicken. As determined in IgE immunoblots and mass analysis, eggs from ancient chicken breeds did not differ in their protein composition. Similar IgE-binding was observed for all egg white preparations, while an elevated allergenicity was detected in egg yolk from Araucana chicken.

CONCLUSION/SIGNIFICANCE

Our results on allergenicity and biological activity do not confirm the common assumption that aboriginal food might be less allergenic. Comprehensive diagnosis of egg allergy should distinguish between reactivity to hen's egg white and yolk fractions to avoid unnecessary dietary restrictions to improve life quality of the allergic child and its family.

The multinational birth cohort of EuroPrevall: background, aims and methods

BACKGROUND/AIM

The true prevalence and risk factors of food allergies in children are not known because estimates were based predominantly on subjective assessments and skin or serum tests of allergic sensitization to food. The diagnostic gold standard, a double-blind placebo-controlled food provocation test, was not performed consistently to confirm suspected allergic reactions in previous population studies in children. This protocol describes the specific aims and diagnostic protocol of a birth cohort study examining prevalence patterns and influential factors of confirmed food allergies in European children from different regions.

METHODS

Within the collaborative translational research project EuroPrevall, we started a multi-center birth cohort study, recruiting a total of over 12 000 newborns in nine countries across Europe in 2005-2009. In addition to three telephone interviews during the first 30 months, parents were asked to immediately inform the centers about possible allergic reactions to food at any time during the follow-up period.

RESULTS

All children with suspected food allergy symptoms were clinically evaluated including double-blind placebo-controlled food challenge tests. We assessed sensitization to different food allergens by measurements of specific serum immunoglobulin E and skin prick tests, collect blood, saliva or buccal swabs for genetic tests, breast milk for measurement of food proteins/cytokines, and evaluate quality-of-life and economic burden of families with food allergic children.

CONCLUSIONS

This birth cohort provides unique data on prevalence, risk factors, quality-of-life, and costs of food allergies in Europe, leading to the development of more informed and integrated preventative and treatment strategies for children with food allergies.

Egg allergy in childhood: an update

PURPOSE OF REVIEW

Allergy to hen's egg is common in infancy and childhood. The management of egg allergy involves dietary avoidance of egg-containing foods, implementation of anaphylaxis precautions and ongoing monitoring for tolerance development. In this article, we review the recent literature regarding the immunology, clinical presentation, diagnosis, management and natural history of egg allergy.

RECENT FINDINGS

Retrospective studies suggest that most egg-allergic children will become tolerant over time. Regular ingestion of small quantities of cooked egg in baked products is often well tolerated and may hasten tolerance development. Influenza vaccination of egg-allergic patients remains controversial, and immunization of patients with previous significant reactions or anaphylaxis to egg is currently not recommended. In recent years, there has been increasing success in clinical trials of specific oral tolerance induction to egg, but concerns regarding the safety and long-term efficacy still preclude the use of oral immunotherapy in clinical practice.

SUMMARY

Egg allergy generally has a good prognosis. Despite recent advances in oral immunotherapy trials, the treatment of egg allergy currently relies on avoidance of egg-containing foods until tolerance has developed. It remains unclear whether the ongoing low-dose exposure to egg proteins in cooked foods improves the natural history of egg allergy.

Oral immunotherapy for food allergy in children

PURPOSE OF REVIEW

Food allergy is a common disease in childhood. Natural tolerance development is frequent, but some children with cow's milk or hen's egg allergy and the majority of children with peanut allergy will remain allergic until adulthood. Within the last several years, the usefulness of oral immunotherapy has been investigated in food allergic patients. This review covers the most recent findings.

RECENT FINDINGS

In cow's milk and hen's egg allergy, controlled trials have been conducted in children, showing that oral immunotherapy, in general, has been successful and safe. Moreover, rush protocols have been developed allowing desensitization in a short period of time. Although side effects are frequent, allergic reactions seem to be controllable by antihistamines, steroids, or epinephrine. For peanut allergy, the first results look promising and detailed data will be available shortly.

SUMMARY

Several studies have shown that oral immunotherapy is a promising approach, especially in patients with severe and persistent food allergy. Side effects are frequent but seem controllable. So far, treatment protocols have been performed in highly supervised research settings. Until more experience is gained from larger long-term studies, oral immunotherapy should not be tried in clinical practice settings.

Safety of a peanut oral immunotherapy protocol in children with peanut allergy

BACKGROUND

Oral immunotherapy (OIT) offers a promising therapeutic option for peanut allergy. Given that during OIT an allergic patient ingests an allergen that could potentially cause a serious reaction, the safety of OIT is of particular concern.

OBJECTIVE

The purpose of this study was to examine safety during the initial escalation day, buildup phase, and home dosing phase in subjects enrolled in a peanut OIT study.

METHODS

Skin, upper respiratory tract, chest, and abdominal symptoms were recorded with initial escalation day and buildup phase dosings. Subjects also maintained daily diaries detailing symptoms after each home dosing. A statistical analysis of these data was performed.

RESULTS

Twenty of 28 patients completed all phases of the study. During the initial escalation day, upper respiratory tract (79%) and abdominal (68%) symptoms were the most likely symptoms experienced. The risk of mild wheezing during the initial escalation day was 18%. The probability of having any symptoms after a buildup phase dose was 46%, with a risk of 29% for upper respiratory tract symptoms and 24% for skin symptoms. The risk of reaction with any home dose was 3.5%. Upper respiratory tract (1.2%) and skin (1.1%) symptoms were the most likely after home doses. Treatment was given with 0.7% of home doses. Two subjects received epinephrine after 1 home dose each.

CONCLUSIONS

Subjects were more likely to have significant allergic symptoms during the initial escalation day when they were in a closely monitored setting than during other phases of the study. Allergic reactions with home doses were rare.

Safe administration of an inactivated virosomal adjuvanted influenza vaccine in asthmatic children with egg allergy

In order to evaluate whether the virosomal adjuvanted influenza vaccine that has been shown to have the lowest egg protein content (Inflexal V, Berna Biotech) could be administered to children with even severe egg allergy without any risk of allergic reactions, we used epicutaneous skin testing with the undiluted vaccine in 88 asthmatic children (44 with and 44 without egg allergy), none of whom had a positive response. They were then vaccinated with the whole dose of Inflexal V intramuscularly in a one-dose protocol, and the occurrence of any immediate or delayed adverse events were actively monitored for 28 days. The results showed the safety of the administration, and demonstrated that Inflexal V can be safely given without performing a vaccine skin test in children with any kind of egg allergy.

Recent advances in the understanding of egg allergens: basic, industrial, and clinical perspectives

The emergence of egg allergy has had both industrial and clinical implications. In industrialized countries, egg allergy accounts for one of the most prevalent food hypersensitivities, especially in children. Atopic dermatitis represents the most common clinical manifestation in infancy; however, the range of clinical signs is broad and encompasses life-threatening anaphylaxis. The dominant egg allergens are proteins and are mainly present in the egg white, for example, ovalbumin, ovomucoid, ovotransferrin, and lysozyme. However, egg yolk also displays low-level allergenicity, for example, alpha-livetin. Strict avoidance of the offending food remains the most common recommendation for egg-allergic individuals. Nevertheless, the omnipresence of egg-derived components in prepackaged or prepared foods makes it difficult. Therefore, more efficient preventive approaches are investigated to protect consumers from inadvertent exposure and ensuing adverse reactions. On the one hand, commercial kits have become readily available that allow for the detection of egg contaminants at trace levels. On the other hand, attempts to produce hypoallergenic egg-containing products through food-processing techniques have met with promising results, but the approach is limited due to its potentially undesirable effects on the unique functional and sensory attributes of egg proteins. Therefore, the development of preventive or curative strategies for egg allergy remains strongly warranted. Pilot studies have suggested that oral immunotherapy (IT) with raw or cooked preparations of egg may represent a safe alternative, immediately available to allergic subjects, but remains applicable to only nonanaphylactic patients. Due to the limitations of conventional IT, novel forms of immunotherapy are sought based on information obtained from the molecular characterization of major egg allergens. In the past decade, promising approaches to the treatment and prevention of egg allergy have been explored and include, among others, the production of hypoallergenic recombinant egg proteins, the development of customized peptides, and bacterial-mediated immunotherapy. Nonspecific approaches have also been evaluated, and preliminary trials with the use of probiotic bacteria have yielded encouraging results. The current understanding of egg allergens offers novel approaches toward the making of food products safe for human consumption and the development of efficient immunotherapeutic strategies.

Egg allergy

Egg allergy is one of the most common food allergies in infants and young children. The great majority is not life-threatening and management involves exclusion of egg from the diet and regular review with the expectation that the majority of children will outgrow the allergy by school age. Judgment is required as to when the dietary elimination of egg is no longer required. This decision may be helped by demonstrating loss of sensitivity by skin prick or specific IgE testing and in some cases a supervised food challenge. Particular issues in management arise with more severe, potentially life-threatening reactions, with immunization with vaccines prepared in eggs, with the diagnosis of egg hypersensitivity as a cause of delayed exacerbations of eczema which can be non-IgE mediated, and in deciding whether a child can be allowed to ingest small amounts of cooked egg through egg-containing foods while continuing to avoid raw egg or larger amounts of whole egg. Cases which illustrate these issues are presented.