Baked egg tolerance: is it possible to predict? / Tolerância aos alimentos assados com ovo: é possível prever quem são esses pacientes?

Abstract Objective: To assess the frequency of baked egg tolerance in IgE-mediated egg allergy patients through the oral food challenge and to assess the tolerance predictability of different skin prick tests, as well as specific serum IgE measurement to egg proteins. Methods: In this cross-sectional study, 42 patients with a diagnosis of egg allergy were submitted to different skin prick tests with egg (in natura, boiled, muffin, ovalbumin, and ovomucoid), and specific IgE to egg white, ovalbumin, and ovomucoid; as well as to the oral food challenge with food containing egg, extensively baked in a wheat matrix. Results: Of the total, 66.6% of patients tolerated the ingestion of egg-containing foods in the oral food challenge. A comparative analysis with positive and negative oral food challenge found no significant differences regarding age, gender, other food allergies, or even specific skin prick tests and IgE values between the groups. Conclusions: The study demonstrated an elevated frequency of baked egg food-tolerant individuals among egg allergy patients. None of the tested markers, skin prick tests, or specific IgE, were shown to be good predictors for identifying baked egg-tolerant patients. The oral food challenge with egg baked in a matrix is central to demonstrate tolerance and the early introduction of baked foods, improving patients' and families' quality of life and nutrient intake.

Resumo Objetivo: Avaliar a frequência de tolerância a alimentos assados com ovo em pacientes com alergia ao ovo mediada por IgE por meio do teste de provocação oral e verificar a capacidade de predição de tolerância ao ovo por meio de teste cutâneo de leitura imediata (Skin Prick Test ou SPT) e de dosagem sérica de IgE específica para componentes do ovo. Métodos: Estudo transversal, 42 pacientes com diagnóstico de alergia ao ovo foram submetidos a SPT com ovo (in natura, cozido, bolinho, ovoalbumina e ovomucoide), IgE específica para clara de ovo, ovoalbumina e ovomucoide e ao teste de provocação oral com alimento com ovo extensamente assado em matriz de trigo. Resultados: Dos pacientes, 66,6% toleraram a ingestão do alimento com ovo durante o teste de provocação oral. Não encontramos diferenças em relação a idade, gênero, outras alergias alimentares ou mesmo entre os valores dos SPT e IgE específica na análise comparativa entre os grupos com teste de provocação oral positivo e teste de provocação oral negativo. Conclusões: Foi demonstrada uma elevada frequência de indivíduos tolerantes a ingestão de alimentos assados com ovo entre os pacientes com alergia a ovo mediada por IgE. Nenhum dos marcadores testados, SPT ou IgE específica, demonstrou ser bom preditor para identificar os pacientes tolerantes. Consideramos que os testes de provocação oral com alimentos com ovo assado sejam fundamentais para a introdução desses assados, melhorar a qualidade de vida e a ingestão de nutrientes dos pacientes e famílias.

A case of anhidrotic ectodermal dysplasia presenting with pyrexia, atopic eczema, and food allergy

Anhidrotic ectodermal dysplasia (AED) is a rare hereditary disorder with a triad of sparse hair, dental hypoplasia, and anhidrosis. Here we report a case of AED with food allergy and atopic eczema. The patient was a 11-month-old boy admitted to our hospital with pyrexia for 2 weeks. He presented with a history of dry skin, eczema, and food allergy to egg. On clinical examination, his body temperature was 38.8°C, with dry skin and eczema almost all over the body, sparse eyebrows, and scalp hair. Laboratory investigations and physical examination did not show any evidence of infection. Radioallergosorbent test was positive to egg yolk, egg white, ovomucoid, milk, house dust, and house dust mite. As the child did not sweat despite the high fever, we performed the sweat test which revealed a total lack of sweat glands. Genetic examination revealed a mutation of the EDA gene and he was diagnosed as AED. His pyrexia improved upon cooling with ice and fan. His mother had lost 8 teeth and her sweat test demonstrated low sweating, suggestive of her being a carrier of AED. Atopy and immune deficiencies have been shown to have a higher prevalence in patients with AED. Disruption of the skin barrier in patients with AED make them more prone to allergic diseases such as atopic eczema, bronchial asthma, allergic rhinitis and food allergy. Careful assessment of the familial history is essential to differentiate AED when examining patients with pyrexia of unknown origin and comorbid allergic diseases.

Update on egg allergy in children

Egg allergy is one of the most common food allergies in children and has a wide spectrum of clinical presentation including anaphylaxis. Many studies suggested egg-specific IgE cutoff values (diagnostic decision point) and skin prick test size that predict a clinical allergic reaction without oral food challenges. Some patients may react to all forms of egg including raw egg, but many egg-allergic patients tolerate baked egg products. A few studies reported that a high concentration of ovomucoid-specific IgE antibody indicates a high risk of reacting to heated egg white. Recently it has been suggested that regular ingestion of baked egg products may hasten tolerance development. Egg allergy may be more persistent than previously thought. The treatment of egg allergy still relies on dietary avoidance of egg-containing foods until tolerance has developed. In recent years there has been increasing success in clinical trials of egg oral immunotherapy, and oral immunotherapy can be a promising treatment modality for providing protection from reactions caused by accidental egg exposure. However, concerns regarding the safety and long-term efficacy still preclude the general use of oral immunotherapy in clinical practice. In this article, the recent literature regarding egg allergens, clinical presentation, diagnosis, management and natural history of egg allergy will be reviewed.

Diagnostic utility of skin prick test to cooked egg in children with egg allergy

PURPOSE: Reliable predictors of tolerance to cooked egg in an egg allergic population are not established. We investigated the usefulness of the skin prick test to cooked egg in children with egg allergy. METHODS: We studied 36 children with egg allergy. Skin prick tests (SPTs) for the uncooked or cooked form of egg white and egg yolk, whole egg, ovomucoid (OVM), and ovalbumin (OVA) were performed at diagnosis. The reagents of cooked egg for SPT were prepared by baking for 25 minutes in 200 degree oven. We also examined specific IgE levels to whole egg, egg white, egg yolk, OVM, and OVA. RESULTS: Patients with history of allergic reaction to extensively heated egg showed significantly increased wheal size for cooked egg white (median [interquartile range]), 10.5 [7.0-14.6] vs. 4.2 [0.0-5.6], P<0.001) and OVM (9.6 [7.3-13.8] vs. 5.6 [0.0-7.8], P=0.001) than those without the history. The strongest positive correlation was found between wheal size for cooked egg white and OVM (r=0.788, P<0.001). SPT wheal size for cooked egg white were positively correlated with serum OVM-specific IgE levels (r=0.691, P<0.001). Cutoff value was 7.0 mm in SPT wheal size for cooked egg white, the sensitivity was 73.1% and specificity was 99.0%. SPT for cooked egg white showed significantly higher area under curve than serum egg white specific IgE. CONCLUSION: Our results suggest that SPT to cooked egg white may be useful predictor of allergic reaction to cooked egg. Further investigations will be needed.

Attenuated Allergenic Activity of Ovomucoid After Electrolysis

Ovomucoid (OMC) is the most prominent allergen causing hen's egg allergy, containing disulfide (S-S) bonds that may be responsible for its allergic action. As S-S bonds may be reduced during electrolysis, this study was undertaken to evaluate modulation of the allergic action of OMC after electrolysis. Electrolysis was carried out for 1% OMC containing 1% sodium chloride for 30 minutes with a voltage difference of 90 V, 0.23 A (30 mA/cm2). Protein assays, amino acid measurement, and mass spectrometry in untreated OMC and OMC on both the anode and cathode sides after electrolysis were performed. Moreover, 21 patients with IgE-mediated hen's egg allergy were evaluated by using the skin prick test (SPT) for untreated OMC and OMC after electrolysis. The allergic action of OMC was reduced after electrolysis on both the anode and cathode sides when evaluated by the SPT. The modifications of OMC on electrolysis caused the loss of 2 distinct peptide fragments (57E-63K and 123H-128R) as seen on matrix-associated laser desorption/ionization time-of-flight mass spectrometry. The total free SH groups in OMC were increased on the cathode side. Although the regions of S-S broken bonds were not determined in this study, the change in S-S bonds in OMC on both the anode and cathode sides may reduce the allergenic activity.

The Influence of the Presence of Wheat Flour on the Antigenic Activities of Egg White Proteins

PURPOSE: It is known that ovomucoid, an egg allergen, is heat resistant and remains soluble after heating. However, a recent study showed that the antigenic activity of ovomucoid could be reduced by heating when egg white (EW) was mixed with wheat flour. This study was performed to determine the influence of wheat flour on the antigenic activities of EW proteins when EW is heated, and the influence of the duration of heat treatment. METHODS: A mixture of EW and wheat flour was kneaded for 10 minutes and then baked at 180degrees C for 10 minutes and 30 minutes. The EW without wheat flour was also heated at 180degrees C for 10 minutes and 30 minutes. The proteins were separated by sodium dodecyl sulfate polyacrylamide gel electrophoresis (SDS-PAGE), and IgE immunoblotting was performed with the pooled sera of 5 egg-allergic patients. The antigenic activities of ovomucoid in different EW samples were measured by inhibition enzyme-linked immunosorbent assay (ELISA). RESULTS: 1) SDS-PAGE: the intensity of the 37-50 kD bands (overlapped bands of ovomucoid and ovalbumin) decreased significantly in the mixture of EW and wheat flour baked for 30 minutes, compared with the mixture baked for 10 minutes, heated EW and raw EW. 2) IgE immunoblot: in the mixture of EW and wheat, a remarkable decrease of IgE reactivity to 37-50 kD was observed when baked for 30 minutes. 3) Inhibition ELISA: the antigenic activity of ovomucoid decreased significantly in the mixture of EW and wheat baked for 30 minutes, but not in the heated pure EW. CONCLUSIONS: This study showed that the antigenic activity of ovomucoid can be reduced by baking EW with wheat flour. The decrease in ovomucoid antigenicity in the baked mixture of EW and wheat flour was dependent on the time of heat treatment, indicating that heating should be prolonged to achieve a reduction in ovomucoid antigenic activity.

The Influence of the Time and Temperature of Heat Treatment on the Allergenicity of Egg White Proteins

PURPOSE: The present study was performed to determine the factor, either duration or the temperature of heat treatment, exerting maximal and significant influence on the composition and allergenicity of egg white (EW) proteins. METHODS: Raw EW and 4 kinds of heated EW (fried EW, boiled EW for 10 minutes, boiled EW for 30 minutes, and baked EW for 20 minutes at 170degrees C) were prepared, and subsequently protein extraction was carried out. The proteins were separated by SDS-PAGE, and then immunoglobulin E (IgE) immunoblots were performed with the sera of 7 egg-allergic patients. Furthermore, the antigenic activities of ovalbumin (OVA), ovomucoid (OM), and ovotransferrin (OT) in different EW samples were measured by inhibition enzyme-linked Immuno-sorbent assay (ELISA). RESULTS: In SDS-PAGE analysis, the intensity of the protein band at 45 kD (corresponding to OVA) decreased significantly in boiled EW (30 minutes) and baked EW, but no change was observed in the case of boiled EW for 10 minutes. In IgE immunoblots, the IgE response to 34-50 kD (OM and OVA) in boiled EW for 30 minutes decreased significantly, when compared with raw EW and other heated EWs. In inhibition ELISA, a significant decrease in the OVA antigenic activity was observed in boiled EW for 30 minutes amongst other heated EW samples. However, OM antigenic activity in all kinds of heated EW including boiled EW for 30 minutes did not reduce after heat treatment. The OT antigenic activity nearly disappeared in heated EWs except in the case of boiled EW for 10 minutes. CONCLUSIONS: Amongst 4 kinds of heated EWs, the boiled EW for 30 minutes showed the most significant changes both in composition and reduction in allergenicity. Our results revealed that the duration of heat treatment had more influence on the composition and allergenicity of EW proteins than the temperature.

Egg Allergy; Immunological and Clinical Aspects / 소아알레르기및호흡기학회지

Egg allergy is a common problem, especially in young children. In most Westernized countries, milk and egg are the most prevalent foods provoking IgE-mediated symptoms of allergy. Allergens in hen's egg have been well defined and possess immunological characteristics specific to the food. In particular, ovomucoid and ovalbumin, the main allergens, can be partially denaturated by cooking. These aspects have clinical implications as some patients might react only to raw and not to cooked egg. Furthermore, this review will address the specificity of the diagnosis of egg allergy as well as specific clinical problems in egg allergic children.

IgE and IgG Immunoblot Patterns to Three Major Egg Allergens : According to the Routes of Sensitization in Atopic Children(<3 Years Old) / 소아알레르기및호흡기학회지

PURPOSE: Atopic dermatitis is a chronic, inflammatory relapsing skin disease fre- quently seen in children with a history of food allergy. Recently, acute allergic reaction to egg in patients with atopic dermatitis who have never been exposed to egg white protein has been reported. The pattern of antigen-antibody reaction by means of IgE and IgG western blotting was analysed to evaluate the possibility of non- dietary sensitization. METHODS: Total 16 children(<3 years old) with egg allergy were enrolled. Eight patients of them had never ingested egg before(Non-dietary sensitization, NDS) and the other 8 patients had a history of previous egg ingestion without significant clinical symptoms(Dietary sensitization, DS). Egg proteins were analysed by SOS-PAGE and antigen-antibody reaction by means of IgE and IgG was deteded by Western-Blotting. RESULTS: The pattern of IgE antibodies to egg white protein were similar in the two groups. IgG Western blotting to egg white in the two groups, the ovotran sferrine and ovalbumin were significantly bound by 100% of sera, respectively. In DS patients, specific IgG antibodies to ovomucoid was significantly bound by 87% (7/8) of sera whereas only 38%(3/8) of sera had detectable specific IgG antibodies against ovomucoid in NDS patients. CONCLUSION: Theses results suggest that specific IgE to egg white related to exposure of egg white protein regar specific IgG to ovomucoid is related to dietary ingestion of egg. Specific IgG to ovalbumin and ovotrans-ferrine show good clinical correlation, further study might be essential to clarify to this hypothesis.