Egg Tolerance Research Articles

Outcomes of Baked Milk and Egg Challenge in Cow’s Milk and Hen’s Egg Allergy: Can Tolerance Be Predicted with Allergen-Specific IgE and Prick-to-Prick Test?

Background: Adding baked food into the diets of patients with cow’s milk allergy (MA) and hen’s egg allergy (EA) has several benefits. Objective: We aimed to determine baked and unbaked food tolerance and evaluate the effectiveness of laboratory findings on the prediction of baked and unbaked food tolerance in patients with MA and EA. Methods: Clinical outcomes of the patients with MA and EA who had been exposed to oral food challenge with baked food were retrospectively analyzed. Results: Ninety-one patients were evaluated. The median age of the study group was 22 months. Forty-nine and 42 patients had IgE-mediated MA and EA, respectively. While all patients with EA tolerated baked egg, 24.5% patients with MA could not tolerate baked cow’s milk (BM). In patients with MA, BM tolerance showed negative association with milk-specific IgE, skin prick test (SPT), and prick-to-prick test (PTP), and the PTP was the most significant parameter (sensitivity 83.8%, specificity 91.7% for PTP ≤7 mm). Negative association was seen between milk-specific IgE, SPT, PTP, and unbaked milk (UBM) tolerance, and PTP was the most significant parameter (sensitivity 100%, specificity 55% for PTP ≤4 mm). In patients with EA, at the end of 6 months of baked hen’s egg (BE) consumption, scrambled egg tolerance showed negative association with egg white-specific IgE level, egg white SPT and PTP. Egg white PTP was the most significant parameter (sensitivity 82.4%, specificity 96.0% for PTP ≤5 mm). Conclusion: Specific-IgE, SPT, and PTP should be kept in mind as parameters that can be used to predict tolerance to BM and BE for patients with MA and EA.

Baked egg tolerance: is it possible to predict?

ObjectiveTo 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. MethodsIn 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. ResultsOf 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. ConclusionsThe 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.

Water relations and drought sensitivity of Folsomia candida eggs (Collembola: Isotomidae)

Drought tolerance of juvenile and adult life stages is relatively well understood, but very little is known about the tolerance of eggs to drought in this group of animals. The aim of the present study was therefore to investigate the water relations and drought sensitivity of eggs of the hygrophilic springtail, Folsomia candida Willem, 1902 (Isotomidae), exposed to a range of soil water potentials above and below the permanent wilting point of plants (-1.5 MPa). Under saturated conditions, eggs absorbed water during development and increased water content from 1.1 to 2.9 mg mg-1 dry weight. By increasing drought conditions, water absorption was gradually reduced and was nullified approximately at the soil water potential equivalent to the osmolality of egg fluids (630 mOsm corresponding to -1.53 MPa). Eggs had a lower permeability for water (68 ± 13 µg water cm-2 h-1 mm Hg-1) than adults (about 400 µg water cm-2 h-1 mm Hg-1), but eggs were much more sensitive to drought than adults. Eggs did not survive exposure to -1.5 MPa, whereas adults readily survive this level of drought by absorbing water vapour. In conclusion, eggs of F. candida are sensitive to drought and would perish if soil water potential in the field approaches the wilting point of plants, which is often reached during summer droughts. The persistence of this species depends on the survival of post-embryonic life stages.

Long term follow up of egg tolerance in egg allergic patients challenged to baked egg.

Long term follow up of egg tolerance in egg allergic patients challenged to baked egg.

Determining Best Tests of Baked Egg Tolerance in Egg Allergic Subjects

Determining Best Tests of Baked Egg Tolerance in Egg Allergic Subjects

Relative reactivity to egg white and yolk or change upon heating as markers for baked egg tolerance.

Hen's egg food allergy is frequent in childhood and phenotypically heterogeneous. Some children can tolerate extensively heated egg. We investigated whether individual relative responses could differentiate children who tolerate baked egg. Reactivities to raw, pasteurized or hard-boiled egg (E), egg white (EW), and egg yolk (EY) fractions were tested by skin prick test (SPT) in 54 egg-allergic children. IgE-sensitization to EW and EY was determined by ImmunoCAP and IgE-binding to EW and 8 EW proteins and to EY and 4 EY sub-fractions by ELISA. Population heterogeneity was assessed by hierarchical ascending classification upon individual variations of reactivity and links between classifications and clinical features by analyzing the contingency tables. All children had positive SPT to raw E and raw EW and 72% to raw EY. Heating decreased SPT-reactivity for some children, pasteurization being less effective than hard-boiling. Children were classed into three classes from relative SPT-reactivity to raw fractions, two from variations of SPT-reactivity with each thermal processing or EW/EY ratio of sensitization, and four from their sensitization pattern. Classifications according to heating were found independent of each other. SPT variations with hard-boiling, IgE-sensitization (ratio or pattern) were linked to allowance by the physicians of egg in baked products. Egg-allergic children were often both sensitized to EY and EW, and heterogeneous patterns of relative responses were evidenced. Irrespective of age and level of sensitization, a low EW/EY ratio or SPT getting null with hard-boiling was found in children allowed to eat baked egg.

Safety and Efficacy Balance of Baked Milk and Egg Oral Immunotherapy

Purpose of review There is a subgroup of individuals with egg or cow’s milk (CM) allergy that can tolerate heated egg or CM. Thermal processing has been shown to affect antigen allergenicity either directly by denaturation of significant epitopes, or indirectly by synergistically altering their susceptibility to the digestion process under specific pH conditions. CM and egg proteins have heat labile molecules that become hypoallergenic after thermal treatment. The allergenicity may be further reduced when the CM and egg allergens are interacting with wheat proteins, and in particular gluten, in an interplay that teleologically affects solubility and therefore bioavailability. This phenomenon is known as the food matrix effect. By exploiting these observations, it has been suggested that diets containing extensively heated CM and egg might comprise an oral immunotherapeutic approach that could alter the expected natural allergy resolution or immunomodulate to tolerance the cases with persistent allergy. Recent findings There is evidence suggesting that most of the baked-tolerant patients can be benefited from baked CM or egg oral immunotherapy (OIT). Following this approach, these patients can be desensitized, can be promoted to a transition from baked CM/egg OIT-induced tolerance to unheated CM and egg OIT-induced tolerance, or may acquire sustained tolerance. Summary Baked CM or egg OIT may accelerate CM or egg allergy resolution and therefore may be a new therapeutic option to etiologically and not just symptomatically treating CM and egg allergy. It remains to be appropriately studied which are the phenotypic characteristics of these patients and which will be the appropriate immunotherapeutic protocol so that OIT can be easily and safely be offered to them.

Randomised controlled trial of a baked egg intervention in young children allergic to raw egg but not baked egg

Background Consumption of baked egg by raw egg allergic children is associated with immune changes suggesting development of tolerance. However, causation has not been tested using a double blind randomized controlled trial (RCT). We aimed to compare clinical and immunological outcomes after baked egg (BE) consumption in young BE tolerant egg allergic children.Methods In a double blind RCT, BE tolerant egg allergic children consumed 10 g BE (1.3 g protein) 2 to 3 times per week for 6 months (n = 21 intervention group) or similar egg free baked goods (n = 22 control group) while maintaining an otherwise egg free diet. The final assessment was a raw egg oral food challenge (OFC) 1 month after ceasing the intervention product. Egg specific IgE and IgG4 were assessed at baseline and 7 months.Results After the intervention there was no difference in raw egg tolerance between groups, (23.5% (4/17) intervention group and 33.3% (6/18) control group). This was independent of age and amount of BE consumed (aOR 0.50 CI 0.11–2.40 p = 0.39). Both groups demonstrated decreased egg specific serum IgE titres and decreased whole egg specific IgE/IgG4 ratios.Discussion We conducted this trial because inclusion of baked egg protein in the diet of egg allergic children appears to move children towards a more tolerant immune profile. Strengths of our study include design of the blinded intervention, the consistent dosing protocol and the regular monitoring of symptoms and intake. However, the study was limited by small sample size resulting in insufficient power to show statistically significant results.Conclusion Our study suggests that short term, regular consumption of BE by BE tolerant 1 to 5 year old children with IgE mediated raw egg allergy may not induce, accelerate or slow development of tolerance to raw egg in this selected population. Trials with larger sample sizes are required to further test this hypothesis.Trial Registration The trial was registered on 7th February 2012 with the Australian New Zealand Clinical Trials Registry (ACTRN 12612000173897).

Matrix effect on baked egg tolerance in children with IgE-mediated hen's egg allergy.

Children with IgE-mediated hen's egg allergy (IgE-HEA) often tolerate baked egg within a wheat matrix. To evaluate the influence of wheat matrix and the effects of little standardized cooking procedures on baked egg tolerance. Fifty-four children with IgE-HEA were enrolled. They underwent prick-by-prick (PbP) tests and open oral food challenges (OFC) performed with baked HE within a wheat matrix (a home-made cake, locally called ciambellone), baked HE without a wheat matrix (in the form of an omelet, locally named frittata) and boiled HE. Three months after passing ciambellone OFC, parents were asked to answer a survey. About 88% of children tolerated ciambellone, 74% frittata, and 56% boiled HE. Negative predictive value of PbP performed with ciambellone, frittata, and boiled HE was 100%. No IgE-mediated adverse reactions were detected at follow-up carried out by the survey. Wheat matrix seemed to be relevant only in few cases. If our results will be confirmed by larger studies, a negative PbP with ciambellone, frittata, or boiled HE will allow patients with IgE-HEA to eat these foods without undergoing OFC. Moreover, our study showed that very strict standardized cooking procedures do not seem to be essential, to guarantee tolerance toward baked HE.

Lethal effects of concentrated CO2 on adult females and eggs of Frankliniella occidentalis and Frankliniella intonsa (Thysanoptera: Thripidae) at a high temperature

Lethal effects of concentrated CO2 at 40 °C on adult females and eggs of Frankliniella occidentalis (Pergande) and Frankliniella intonsa (Trybom) were examined. No female adult of F. occidentalis survived after 3 h exposure to 10 % CO2. No female adult of F. intonsa survived after 3 h exposure to 30 % CO2. Tolerance of eggs to CO2 exposure was higher than that of female adults and increased as the egg stage progressed in both species. To achieve 100 % mortality of 2-day-old eggs of F. occidentalis and F. intonsa, 3 h treatment of 40 % CO2 and 5 h treatment of 50 % CO2 or 6 h treatment of 40 % CO2 were required, respectively. These results suggest that thrips can be controlled with less CO2 concentration and shorter exposure time at a high-temperature condition.

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

Background Children do not always outgrow hen’s egg allergies in early childhood. Because egg yolks are less allergenic than egg whites, we performed an oral food challenge with heated egg yolk slightly contaminated with egg white (EYSEW OFC) in infants allergic to hen’s egg. We hypothesized that the EYSEW OFC results would predict the egg allergy’s natural course.Methods We retrospectively reviewed participants with hen’s egg allergy who underwent their first EYSEW OFC at 12–23 months of age between 2004 and 2010. Participants who passed the first EYSEW OFC were defined as EYSEW-tolerant, and participants who failed the OFC were defined as EYSEW-reactive. Participants who passed the EYSEW OFC underwent an OFC with half of a heated whole egg (WE OFC). Participants who passed a WE OFC were defined to be heated hen’s egg-tolerant. Participants who failed the EYSEW OFC or the WE OFC underwent another OFC at least 6 months later. We compared tolerance to heated hen’s egg at 36 months after the first EYSEW OFC between EYSEW-tolerant and EYSEW-reactive participants. Univariate and multivariate logistic regression analyses were conducted.Results Of the 197 included participants (median age: 18.3 months; range: 12.1–23.8 months), 179 (90.9%) were EYSEW tolerant and 18 (9.1%) were EYSEW reactive. At 36 months after the first EYSEW OFC, 164 EYSEW-tolerant (91.6%) and 12 EYSEW-reactive participants (66.7%) achieved heated hen’s egg tolerance. In the univariate logistic regression analyses, EYSEW-reactive participants (crude odds ratio [OR], 5.5 [95% confidence intervals [CI], 1.8–16.6]; p = 0.003) and those with baseline egg white sIgE levels (crude OR: 3.9 per ten-fold increase [95% CI, 1.5–10.2]; p = 0.005) had greater odds of persistent allergy to hen’s egg at 36 months after the first EYSEW OFC. In a multivariate logistic regression analysis after adjustment for baseline egg white sIgE, EYSEW-reactive participants had greater odds of persistent allergy to hen’s egg than EYSEW-tolerant participants (adjusted OR: 4.6 [95% CI, 1.5–15.0]; p = 0.003).Conclusions Classifying infants who are allergic to hen’s egg into EYSEW tolerant and EYSEW reactive groups was useful in determining prognosis.

Debates in allergy medicine: baked milk and egg ingestion accelerates resolution of milk and egg allergy

Cow’s milk and hen’s egg are ubiquitous in diets around the world and can be important sources of protein in young children. Unfortunately, milk and egg allergies are also some of the most common food allergies in childhood. Less allergenic forms of milk and egg due to heating and interactions with a food matrix, as in baked goods, are tolerated by a majority of milk- and egg-allergic patients. Adding baked milk and egg into the diets of milk- and egg-allergic children can broaden diets, increase nutrition, and improve quality of life. Most important, regular ingestion of baked milk and egg can help children outgrow their allergies to milk and egg. This article will review our current understanding of baked milk and egg tolerance and outline how these baked forms accelerates tolerance to regular milk and egg.

The Editor takes a closer look at some of this month's articles

The Editor takes a closer look at some of this month's articles

Comparative Egg Morphology and Chorionic Ultrastructure of Key Stored-Product Insect Pests

Eggs of Tribolium castaneum (Herbst) (Coleoptera: Tenebrionidae) and Plodia interpunctella (Hubner) (Lepidoptera: Pyralidae) were imaged with scanning electron microscopy to explore how respiratory openings on the chorion surface may be related to the efficacy of fumigants. Each P. interpunctella egg had many aeropyles and several micropyles, whereas each T. castaneum egg had neither aeropyles nor micropyles. Transmission electron microscopy was used to obtain cross sectional images of chorions, with eggs of T. castaneum , P. interpunctella , Carpophilus hemipterus (L.) (Coleoptera: Nitidulidae), and Amyelois transitella (Walker) (Lepidoptera: Pyralidae) each having unique chorionic ultrastructure. The types of layers and relative thicknesses of different layers of the chorion varied across species. Exochorion of lepidopteran eggs was a lamellate structure and the thickest layer, whereas crystalline endochorion was the thickest layer in coleopterans. Although quantitative data on fumigant uptake by eggs of different insect species are needed, the findings of the current study suggest that species-specific tolerance of eggs to fumigants may partly be explained by differences in respiratory structures and chorion characteristics.

Cold tolerance of Colorado potato beetle (Leptinotarsa decemlineata Say) adults and eggs

The cold tolerance of different seasonal groups (pre-diapause, diapauses and post-diapause) of Colorado potato beetle (Leptinotarsa decemlineata Say) was assessed by exposing them either to a constant temperature of –3°C for 48 to 624 h, or to –3, −4, −5, −6 or −7 °C for a constant 24 h. Cold survival was affected by the length of exposure, by the temperature rates and by seasonality. The least cold-tolerant were pre-diapause beetles in August with a mean lethal temperature (Ltemp50) of −4.4°C for 24 h exposure and with a lethal time (Ltime50) of 106.8 h at −3°C. Cold tolerance was significantly higher in the diapause group in January and in the post-diapause group in March; it did not differ significantly between these groups of beetle for 24 h exposure, the lethal temperature being −5.8°C for both groups. Seasonality had a greater influence on survival of these groups after longer exposure to constant mild sub-zero temperature (−3°C); in diapause group, all the beetles survived 624 h exposure, but in post-diapause group the survival limit decreased to 216 h and lethal time was 153.9 h. Colorado potato beetle eggs tolerated 24 h exposure to sub-zero temperatures from −3°C to −5°C or longer exposure at −3°C for 72 h without a reduction in hatchability. The mean lethal time for 50% mortality of eggs was 76.5 h and mean lethal temperature was −5.8°C. Thus, we conclude that night frosts common in northern regions do not damage Colorado potato beetle adults or eggs to the extent that might threaten the survival of the population.

Ovalbumin‐specific IgE/IgG4 ratio might improve the prediction of cooked and uncooked egg tolerance development in egg‐allergic children

Accurate predictors of natural tolerance development to cooked and uncooked egg are needed in egg-allergic patients. To compare the diagnostic performance of different immunological tests in relation to egg allergy versus tolerance. Children aged 5-18 years diagnosed with IgE-mediated egg allergy were prospectively recruited. All followed an egg-free diet. Prick test and specific IgE (sIgE) to ovalbumin, ovomucoid and egg white, ovalbumin-sIgG4 and ovomucoid-sIgG4 were determined. By boiled and raw egg challenges, children were classified as cooked egg allergic (CEA, n = 50) or tolerant (CET, n = 35), and uncooked egg allergic (UEA, n = 64) or tolerant (UET, n = 21). Statistics. Comparative analysis (CEA vs. CET and UEA vs. UET). Multivariate logistic regression. Partial receiver operating characteristic curve analysis of tests in relation to CEA and UEA. Negative decision points were defined as cut-offs with sensitivity 95%. Ovalbumin-sIgG4 resulted an independent protective factor for uncooked egg allergy. To identify patients with high probability of egg tolerance, ovalbumin-sIgE/sIgG4 tended to perform better than sIgE and prick, specifically in children with ovalbumin-sIgE < 1.9 kU/L (for UEA) and ovomucoid-sIgE < 2.12 kU/L (for CEA). The most accurate cut-offs to recommend challenges were ovalbumin-sIgE/sIgG4 below 2.49 for cooked egg and 1.45 for uncooked egg, which associated 89.5% and 80% probability of tolerance (negative likelihood ratios 0.08 and 0.06), respectively. These cut-offs identified correctly as tolerant an additional 23% and 14% of children with negative challenges to cooked and uncooked egg, respectively, in comparison with sIgE negative decision points. Additionally, prick test tended to perform better than sIgE alone in predicting cooked and uncooked egg tolerance for ovomucoid-sIgE < 0.92 kU/L and ovalbumin-sIgE < 1.37 kU/L, respectively. Ovalbumin-specific IgG4 is an independent predictor of tolerance development to uncooked egg. Ovalbumin-sIgE/sIgG4 ratio, followed by skin prick test (SPT), seems to perform better than sIgE in identifying egg-allergic children with high probability of tolerance to cooked and uncooked egg over follow-up.

The natural history and clinical predictors of egg allergy in the first 2 years of life: A prospective, population-based cohort study

There is a paucity of data examining the natural history of and risk factors for egg allergy persistence, the most common IgE-mediated food allergy in infants. We aimed to assess the natural history of egg allergy and identify clinical predictors for persistent egg allergy in a population-based cohort. The HealthNuts study is a prospective, population-based cohort study of 5276 infants who underwent skin prick tests to 4 allergens, including egg. Infants with a detectable wheal were offered hospital-based oral food challenges (OFCs) to egg, irrespective of skin prick test wheal sizes. Infants with challenge-confirmed raw egg allergy were offered baked egg OFCs at age 1 year and follow-up at age 2 years, with repeat OFCs to raw egg. One hundred forty infants with challenge-confirmed egg allergy at age 1 year participated in the follow-up. Egg allergy resolved in 66 (47%) infants (95% CI, 37% to 56%) by 2 years of age; however, resolution was lower in children with baked egg allergy at age 1 year compared with baked egg tolerance (13% and 56%, respectively; adjusted odds ratio, 5.27; 95% CI, 1.36-20.50; P = .02). In the subgroup of infants who were tolerant to baked egg at age 1 year, frequent ingestion of baked egg (≥5 times per month) compared with infrequent ingestion (0-4 times per month) increased the likelihood of tolerance (adjusted odds ratio, 3.52; 95% CI, 1.38-8.98; P = .009). Mutation in the filaggrin gene was not associated with the resolution of either egg allergy or egg sensitization at age 2 years. Phenotyping of egg allergy (baked egg tolerant vs allergic) should be considered in the management of this allergy because it has prognostic implications and eases dietary restrictions. Randomized controlled trials for egg oral immunotherapy should consider stratifying at baseline by the baked egg subphenotype to account for the differential rate of tolerance development.

Marine spawning sites of perch Perca fluviatilis revealed by oviduct-inserted acoustic transmitters

AB Aquatic Biology Contact the journal Twitter RSS Mailing List Subscribe to our mailing list via Mailchimp HomeLatest VolumeAbout the JournalEditorsTheme Sections AB 19:201-206 (2013) - DOI: https://doi.org/10.3354/ab00529 Marine spawning sites of perch Perca fluviatilis revealed by oviduct-inserted acoustic transmitters Mikkel Skovrind1, Emil A. F. Christensen1,*, Henrik Carl1, Lene Jacobsen2, Peter R. Møller1 1University of Copenhagen, Natural History Museum of Denmark, Universitetsparken 15, 2100 Copenhagen, Denmark 2DTU Aqua, Technical University of Denmark National Institute of Aquatic Resources, Section for Freshwater Fisheries Ecology, Vejlsøvej 39, 8600 Silkeborg, Denmark *Corresponding author. Email: mts447@alumni.ku.dk ABSTRACT: In the 1970s, a flood-protection system dramatically changed a large part of the coastal environment of Køge Bugt, a bay in the western Baltic Sea, from open coast to a brackish lagoon habitat. An anadromous stock of European perch Perca fluviatilis seems to have benefitted from this change, but details about their spawning behavior remain unknown. We used oviduct-inserted acoustic transmitters to reveal the pre-spawning behavior and spawning sites of this population. Thirteen female perch were caught in the lower stream basin of St. Vejle Å, and were tagged with acoustic transmitters inserted through the oviduct. The fish were tracked from March 2 to May 24, 2012 with both passive and active telemetry systems. The pre-spawning behavior involved short trips between the stream and adjacent lagoons. Twelve of the 13 transmitters (92%) were expulsed during spawning, providing for the first time a strong proof of concept of oviduct-inserted acoustic transmitters in brackish and marine fish spawning studies. The transmitter expulsions were validated using an egg map, which was based on visual observations of perch egg-strands, and 11 of the 12 expulsed transmitters (92%) were located in areas with eggs. Many fish spawned in the brackish water with salinities up to 9.6 PSU. These salinities are higher than those previously observed for European perch spawning in the wild, and call for further investigations of salinity tolerance in perch eggs. KEY WORDS: Acoustic telemetry · Oviduct · European perch · Salinity · Spawning · Brackish water Full text in pdf format NextCite this article as: Skovrind M, Christensen EAF, Carl H, Jacobsen L, Møller PR (2013) Marine spawning sites of perch Perca fluviatilis revealed by oviduct-inserted acoustic transmitters. Aquat Biol 19:201-206. https://doi.org/10.3354/ab00529 Export citation RSS - Facebook - Tweet - linkedIn Cited by Published in AB Vol. 19, No. 3. Online publication date: October 24, 2013 Print ISSN: 1864-7782; Online ISSN: 1864-7790 Copyright © 2013 Inter-Research.

Frequent Baked Egg Ingestion Was Not Associated With Change in Rate of Decline in Egg Skin-Prick Test in Children With Challenge-Confirmed Egg Allergy

To determine if the natural history of egg allergy would be altered by the frequent ingestion of baked egg in food challenge–confirmed egg-allergic children.A retrospective clinical cohort study of 125 children from the Department of Allergy and Immunology, Royal Children’s Hospital, Victoria, Australia, was completed. Participants from 1996 to 2005 with challenge-proven egg allergy were included, providing they had at least 2 egg skin-prick tests performed within this period.A telephone questionnaire was conducted to assess the frequency of baked egg ingestion as follows: (1) frequent (more than once per week), (2) regular (more than once every 3 months, up to once per week or less), or (3) strict avoidance (once every 3 months or less). A multiple linear regression analysis, adjusting for possible confounders, was used to examine the relationship between frequency of baked egg ingestion and the rate of decline in egg skin-prick test size.The mean rate of decline in egg skin-prick test size in all children was 0.7 mm per year (95% confidence interval [CI] 0.5–1.0 mm per year). The frequency of baked egg ingestion did not affect the rate of decline in egg skin-prick test size (P = .57). Individual results for each group were as follows: frequent ingestion (n = 21, mean 0.4 mm per year, 95% CI 0.3–1.2 mm per year), regular ingestion (n = 37, mean 0.9 mm per year, 95% CI 0.4–1.4 mm per year), and strict avoidance (n = 67, mean 0.7 mm per year, 95% CI 0.4–1.1 mm per year).Frequent baked egg ingestion was not associated with a different rate of decline in egg skin-prick test compared with strict avoidance in egg-allergic children.This study is different from previous studies from the Mount Sinai, New York, group (J Allergy Clin Immunol. 2008;122;977–983; J Allergy Clin Immunol. 2012;130(2):473–480) who have shown that regular ingestion of heated egg (defined as 1–3 servings per day) was associated with decreased skin-prick test wheal diameters to egg white and decreasing egg white, ovalbumin, and ovomucoid-specific immunoglobulin E antibody levels. This study does not specify the frequency of baked egg ingestion in the more than once a week group. It appears that this dosing interval may be critical to make the most impact immunologically. Clearly, ingestion once every 3 months or strict avoidance of egg does not appear to accelerate the development of egg tolerance.

Turning up the heat on skin testing for baked egg allergy

Egg allergy is one of the most common causes of pediatric food allergy [1–3]. Egg is an important source of nutrition and commonly found in commercial food products such as baked goods. Strict avoidance of egg can impair quality of life by limiting the number of allowed foods and making social events involving food potentially dangerous, stressful and isolating. Although most children eventually tolerate egg, children are outgrowing their egg allergies later than previously reported [4]. Recent studies suggest that most egg-allergic children may tolerate baked egg products [5–9]. Identification of predictable markers to identify these patients has high potential to aid physicians in clinical management of egg allergy. The prospective study by Tan et al. [10] published in this issue of the Journal investigates the role of skin prick testing (SPT) to ovomucoid and a baked egg muffin in predicting outcomes of baked egg challenges. The authors found that SPT measurements to egg white, ovomucoid and baked egg were significantly larger in those who failed baked egg challenges, compared to those who passed. Their results regarding egg white SPT are in agreement with previously reported data [7–9, 11]. The findings that ovomucoid and baked egg SPT may be useful in predicting baked egg challenge outcome are novel. Ovomucoid, the dominant allergen in egg white, is relatively stable to thermal processing and proteolysis, which may explain its importance as an allergen [12]. As such, several studies have also demonstrated the potential importance of immune response to ovomucoid in predicting baked egg tolerance [8, 11, 13–15], but its true utility is controversial. We have recently shown that while ovomucoid specific IgE (sIgE) predicts outcomes of baked egg challenges, it is not superior to egg white sIgE or SPT, which remain useful predictors of baked egg tolerance [9]. Baking exposes proteins to high temperatures, which may reduce allergenicity by destroying conformational epitopes. In addition, allergenicity may be decreased by blocking epitope access through interaction with other food proteins, such as in a wheat matrix in a baked muffin [16]. There is presently no diagnostic test available to assess immune response to the egg proteins in a wheat complex, which represents a significant knowledge gap in current clinical practice. The utility of SPT to baked egg has been investigated in a small retrospective study and a negative SPT to baked egg was found to predict passing a baked egg challenge, but predictive values of positive SPTs were not further explored [17]. SPT can be performed quickly and inexpensively, making this test available to many practicing allergists. Unfortunately, ovomucoid SPT extract is not currently commercially available in certain countries such as the United States. SPT to fresh muffin may best reflect the degree of egg protein modification that a patient is exposed to in a baked egg challenge. Therefore, SPT to baked egg may prove to be an important predictor of baked egg challenge outcome. SPT to the fresh baked good may also be useful in identifying children who may be tolerant to heated but even less well-baked forms of egg. SPT to brownies, meatballs, pancakes or even gooey cookies may be on the horizon of allergy testing. This study is limited in several aspects that suggest the need for future studies. Egg allergy was defined based on history of reported reaction to egg and/or positive testing, rather than a formal physician-observed food challenge, and not all children had a history of reactions to egg. Food challenges to investigate whether the children who passed baked egg challenges could also consume unheated egg were not done. Since baked egg SPT was done by creating a homogenate of the muffin, it is possible that concentrations and modifications of egg proteins may vary depending on what portion of the muffin was sampled (e.g., crust versus inner layer). Direct comparisons between other existing SPT and sIgE tests were not done to analyse whether one test was superior. So, while potentially useful, ovomucoid and baked egg SPT should not replace other existing testing methods. Nevertheless, this study adds to the growing body of literature aimed at identifying predictors of baked egg challenge outcomes. SPT to baked egg and ovomucoid are novel and potentially useful ways to rapidly and inexpensively identify children who may pass a baked egg challenge. The utility of baked egg and ovomucoid SPT needs to be evaluated further before recommending these tests for the diagnosis of baked egg allergy in clinical practice.