Total serum IgE level influences oral food challenge tests for IgE-mediated food allergies

Predicting the Outcome of Pediatric Oral Food Challenges for Determining Tolerance Development

PURPOSE

Despite the risk of anaphylaxis, oral food challenges (OFCs) are performed clinically for various indications, particularly to confirm tolerance development. This study aimed to assess OFCs by relevant indications and build an outcome prediction model to help determine when to perform OFCs in children who are likely to have developed immune tolerance.

METHODS

In total, 432 pediatric OFCs were retrospectively analyzed according to indications. Clinical characteristics, serum total immunoglobulin (Ig) E, blood eosinophils, and specific IgE and IgG4 levels for food allergens were noted and compared. Machine learning was utilized to select the most important variables in determining the passage of the OFCs, and prediction models were constructed using the selected variables.

RESULTS

OFCs were most commonly performed to confirm tolerance development (number, %; 267, 61.8%). The most common food allergens tested were egg (191, 44.2%) and milk (135, 31.3%). Children who passed the egg challenges for confirming tolerance acquisition had significantly lower egg white-specific IgE level (P = 0.008). Similarly, those who passed milk challenges had significantly lower cow's milk-specific IgE (P = 0.002) and casein-specific IgE levels (P = 0.005). We developed a nomogram to predict the outcome of OFCs to determine the tolerance acquisition with the selected variables; lower food-specific IgE, higher total IgE, and younger age indicated a higher probability of passage. The area under the curve (95% confidence interval) was 0.623 (0.503-0.743) for egg and 0.734 (0.628-0.840) for milk.

CONCLUSIONS

Serum total IgE and food-specific IgE combined with age showed trends toward passing OFCs for confirming tolerance development. The constructed model may be used by clinicians as a practical guide for minimizing the risks of OFCs and a timely reintroduction for children with food allergies.

Jug r 1 sensitization in 0- to 35-month-old children with egg, milk, or wheat sensitization

Background

The incidence of tree nut allergies in children is increasing, with walnut allergy being the most common in the United States and Japan. Allergic reactions, including anaphylaxis, frequently occur at the first intake of tree nuts, suggesting prior sensitization.

Objective

Our aim was to identify which children should be considered for workup for preexisting sensitization.

Methods

Juglans regia (Jug r) 1-specific IgE screening for 0- to 35-month-old children who had a positive specific IgE result for egg white, milk, or wheat and had never ingested walnuts was conducted at a food allergy referral hospital between November 2018 and December 2022. Clinical data regarding age; sex; allergic disease complications; and egg, milk, or wheat allergy were examined retrospectively.

Results

The rate of Jug r 1-specific IgE positivity (level > 0.34 kUA/L) of 205 children (125 of whom were boys) was 9.8%, with a median Jug r 1-specific IgE level of 12.5 kUA/L in patients with a positive test result. Eczema was observed in 119 patients (58%). The rate of Jug r 1-specific IgE positivity was significantly higher in the eczema-positive group (15.1% [18 of 119]) than in the eczema-negative group (2.3% [2 of 86]) (P = .002). In the eczema-positive group, the rates of Jug r 1-specific IgE positivity per sensitized antigen were 13.7% for egg, 17.0% for milk, and 17.1% for wheat. The rate of Jug r 1-specific IgE positivity was significantly higher in the group with severe eczema (26.6% [17 of 64]) than in the group with nonsevere eczema (1.8% [1 of 55]) (P < .001).

Conclusion

Even in children younger than 3 years, 15% of children with eczema and egg, milk, or wheat sensitization were sensitized to Jug r 1.

IgE-mediated cow's milk allergy in Brazilian children: Outcomes of oral food challenge

Background

Oral food challenge (OFC) is useful for diagnosing food allergies and assessing tolerance, but severe reactions may occur during the procedure.

Objective

To characterize the frequency and severity of reactions during cow's milk (CM) OFCs.

Methods

A cross-sectional study was conducted to analyze the outcome of cow's milk oral food challenges (CMOFCs) performed to confirm IgE-mediated CM allergy or to assess food tolerance. CM was given first as baked milk (BM), followed by whole CM if there was no prior reaction to BM. An OFC was considered positive if IgE-mediated symptoms developed up to 2 h after ingestion. Symptoms were described and variables including age at OFC, prior anaphylaxis, other atopic diseases, and skin test results were compared according to the OFC outcomes.

Results

A total of 266 CMOFCs were performed, including 159 patients with a median age of 6.3 years old. One hundred thirty-six tests were positive and 62 resulted in anaphylaxis. Thirty-nine anaphylactic reactions were observed up to 30 min after the first dose. Severe anaphylaxis (cardiovascular and/or neurological involvement) was reported in 5 tests. A second dose of epinephrine was required in 3 tests, and 1 presented a biphasic response. Younger patients had a higher risk of anaphylaxis during baked milk oral food challenge (BMOFC) (p = 0.009). The frequency of anaphylaxis was higher in patients submitted to BM (p = 0.009).

Conclusions

Anaphylaxis is a known complication of CMOFCs even when there is no prior anaphylaxis or when conducted with baked products. This study reinforces the importance of conducting OFC in appropriate settings with a well-trained team.

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.

Total serum IgE levels as predictor of the acquisition of tolerance in children with food allergy: Findings from a pilot study

BACKGROUND

The gold standard to diagnose food allergy (FA) is a double-blind, placebo-controlled food challenge (OFC), even if it shows potential risk of severe allergic reactions for the patient and is time-consuming. Therefore, easier, and less invasive methods are needed to diagnose FA and predict the tolerance, changing the clinical practice.

AIM

The main aim of this study was to assess whether the total IgE values at the diagnosis of FA were associated with the duration of the tolerance acquisition and thus of the food elimination diet.

METHODS

We retrospectively analyzed the medical records of 40 patients allergic to milk or egg who performed an OFC for the reintroduction of the causal food at the Pediatric Allergy and Respiratory Unit of the University of Chieti from January 2018 to December 2020.

RESULTS

We found a positive association of total serum IgE with the elimination diet duration (β = 0.152; CI, 95% 0.04-0.27) after adjusting for age, sex, and type of allergy (milk or egg). We also showed a significant correlation (r = 0.41 and p-value = 0.007) between the total IgE values and the duration of the elimination diet and a significant correlation between the casein specific IgE values at diagnosis of FA and the severity of the clinical presentation (r = 0.66; p-value 0.009).

CONCLUSION

Total serum IgE at baseline, along with the downward trend of food-specific IgE levels (to milk or egg), may be useful in the prognostication of natural tolerance acquisition.

Peanut diversity and specific activity are the dominant IgE characteristics for effector cell activation in children

Background

IgE mediates allergic reactions to peanut; however, peanut-specific IgE (sIgE) levels do not always equate to clinical peanut allergy. Qualitative differences between sIgE of peanut-sensitized but tolerant (PS) and peanut-allergic (PA) individuals may be important.

Objective

We sought to assess the influence of IgE characteristics on effector cell activation in peanut allergy.

Methods

A cohort of 100 children was studied. The levels of IgE to peanut and peanut components were measured. Specific activity (SA) was estimated as the ratio of allergen-sIgE to total IgE. Avidity was measured by ImmunoCAP with sodium thiocyanate. IgE diversity was calculated on the basis of ImmunoCAP-Immuno Solid-phase Allergen Chip assays for 112 allergens or for 6 peanut allergens. Whole-blood basophils and mast cell line Laboratory of Allergic Diseases 2 sensitized with patients’ plasma were stimulated with peanut or controls and assessed by flow cytometry.

Results

SA to peanut (P < .001), Ara h 1 (P = .004), Ara h 2 (P < .001), Ara h 3 (P = .02), and Ara h 6 (P < .001) and the avidity of peanut-sIgE (P < .001) were higher in PA than in PS individuals. Diversity for peanut allergens was greater in PA individuals (P < .001). All IgE characteristics were correlated with basophil and mast cell activation. Peanut SA (R = 0.447) and peanut diversity (R = 0.440) had the highest standardized β-coefficients in combined multivariable regression models (0.447 and 0.440, respectively).

Conclusions

IgE specificity, SA, avidity, and peanut diversity were greater in PA than in PS individuals. IgE peanut SA and peanut diversity had the greatest influence on effector cell activation and could be used clinically.

The effect of age, sex, race/ethnicity, health insurance, and food specific serum immunoglobulin E on outcomes of oral food challenges

Background

Although oral food challenge (OFC) is an important clinical procedure for diagnosing food allergy, there is a paucity of literature on the outcome of the procedure and specifically the patients on whom the procedure is performed from the aspects of their age, sex, race/ethnicity, health insurance status, and serum specific IgE to the food tested.

Objective

We aimed to review results of OFC and determine the impact of patient age, sex, race/ethnicity, insurance status, private or public, and food specific serum IgE on the outcome of OFC.

Methods

A retrospective chart review was performed of patients undergoing OFCs at a children's hospital outpatient allergy clinic over a two-year period. The outcome of OFC was allergic or non-allergic based on determination and documentation by the treating physician. A logistic regression model was built to determine the association between the OFC outcomes, age, and symptoms at the time of OFC. A Chi-square analysis was performed to check for any significant relationship between the OFC outcome and age when stratified by insurance status.

Results

Five hundred and eight children underwent 641 OFCs. Twenty nine percent of OFCs had an allergic outcome with the most commonly challenged foods being peanuts, eggs, and milk. Patient age and gender, when stratified by insurance status, did not have a significant effect on OFC outcomes. Serum IgE to peanuts and egg was significantly different between allergic OFC and non-allergic outcome. Vomiting and urticaria/angioedema correlated with an allergic OFC outcome.

Conclusion

OFCs confirm the food allergy diagnosis in about one-third of patients tested, and they should continue to be used when possible for an accurate diagnosis. Age, sex, and insurance status do not have a significant association with the outcome of OFC and cannot be added as predictive factors.

Allergy in an Evolutionary Framework

Respiratory allergy including bronchial asthma and food allergy have gained epidemic character in the last decades in industrialized countries. Much has been learned with respect to the pathophysiology of allergic disease and this has facilitated specific therapies. Allergy is a chronic disease, and being so prevalent claims to search for evolutionary causes of the general susceptibility of humans as a species to react to environmental antigens in a Th2 type immune reaction with IgE production. In an evolutionary analysis of Allergy, necessary questions addressed in this review are "Why does IgE exist or why did IgE evolve?" as well as from the point of view of the mismatch hypothesis, "Why is there an Allergy epidemic?" Recent studies on the possible biological and protective role of IgE against parasites, arthropods, venoms or toxins are challenging the widely accepted definition of allergens as generally innocuous antigens. Combining the immunologic danger model and the toxin hypothesis for allergies, the allergic response could have evolved with an adaptive value and allergens could be proxies for other putative noxious agents. The last decades yielded with vast molecular data of allergens. With available bioinformatics tools, we therefore also describe that evolutionary theory could be applied to prevent allergy, estimate cross-reactivity, to design allergen-specific immunotherapy and to assess the risks of novel foods.

Risk prediction of severe reaction to oral challenge test of cow's milk

Cow's milk is one of the most common food allergens among children. Oral food challenge tests determine the threshold dose of allergens, but have not been standardized. To reduce the severe reactions, we developed a practical model of the test. We studied 111 high-risk patients who underwent a first milk oral food challenge on the risk-stratified dose between 2011 and 2017 for predicting the severe reaction risk. Severe reactions were defined as showing > 3 of Sampson's classification grade. Twenty-eight patients (25%) showed severe reactions without death. Prior to oral food challenge, severe reaction patients experienced milk avoidance (71% vs. 45%, p = 0.02) or bronchial asthma (61% vs. 28%, p = 0.003) more frequently and showed higher milk-specific IgE levels (median 28.3 vs. 7.7 U_A/mL, p < 0.0001) than non-severe reaction patients. Multivariate logistic regression analyses established a formula including severe reaction-associated factors; increased levels of milk-specific IgE (odds ratio 11.61, p = 0.001), milk avoidance (odds ratio 3.88, p = 0.02), and bronchial asthma (odds ratio 3.75, p = 0.02). This model had 86% sensitivity and 56% specificity (cut-off 0.25) for risk. Five patients with < 25% probability developed severe reactions, which started in > 3 grade dyspnea up to 20 mL of challenge.Conclusion: This model could effectively reduce the severe reaction development on the first milk oral food challenge test according to the individual needs. What is Known: •Higher levels of milk-specific IgE values, bronchial asthma, and complete milk avoidance are independent risk factors of severe reactions during the cow's milk oral food challenge. What is New: •Statistical analyses of our milk oral food challenge records for 111 patients helped us develop a model formula predicting severe reactions at the first test with high specificity and sensitivity. •This simple risk-stratified protocol is useful for minimizing the adverse events in the first milk challenge.

Baker's Asthma: Is the Ratio of Rye Flour-Specific IgE to Total IgE More Suitable to Predict the Outcome of Challenge Test Than Specific IgE Alone

Usually the diagnosis of baker's asthma is based on specific inhalation challenge with flours. To a certain extent the concentration of specific IgE to flour predicts the outcome of challenge test in bakers. The aim of this study was to evaluate whether the ratio of specific IgE (sIgE) to total IgE (tIgE) improves challenge test prediction in comparison to sIgE alone. Ninety-five bakers with work-related respiratory symptoms were challenged with rye flour. Total IgE, sIgE, and the sIgE/tIgE ratio were determined. Receiver operator characteristic (ROC) plots including the area under the curve (AUC) were calculated using the challenge test as gold-standard. Total IgE and sIgE concentrations, and their ratio were significantly higher in bakers with a positive challenge test than in those with a negative one (p < 0.0001, p < 0.0001, and p = 0.023, respectively). In ROC analysis, AUC was 0.83 for sIgE alone, 0.79 for tIgE, and 0.64 for the ratio. At optimal cut-offs, tIgE, sIgE, and the ratio reached a positive predicted value (PPV) of 95%, 84% and 77%, respectively. In conclusion, calculating the ratio of rye flour-sIgE to tIgE failed to improve the challenge test prediction in our study group.

Innovation in Food Challenge Tests for Food Allergy

PURPOSE OF REVIEW

This review incorporates findings from studies of oral food challenges (OFC) over the last decade and highlights the latest innovations and understanding of the procedure.

RECENT FINDINGS

PRACTALL guidelines are widely used in OFC research, but there is still no international consensus on the OFC protocol in clinical practice. Guidelines for performing OFC in clinical practice have been updated to include oral food challenges for infants. There have been advances in predictive models for outcomes and severity of reaction during OFC that take into account multiple clinical data as well as newer laboratory modalities. Low-dose OFC and eliciting threshold dose determination are being examined for additional diagnostic and therapeutic use in the management of food allergy. Quality-of-life considerations have also been reviewed, as well as post-OFC assessment and care. The OFC remains an important diagnostic tool in the management of food allergy and in clinical research. Advances in the field should improve safety and broaden the clinical applications of this essential procedure.

Follow-up of patients with uncertain symptoms during an oral food challenge is useful for diagnosis

BACKGROUND

Uncertain symptoms often emerge during an oral food challenge (OFC), and Open-OFCs with those uncertain mild symptoms are ordinarily regarded as positive. Double-blind placebo-controlled food challenges should be conducted to determine these associations. Nevertheless, studies regarding the diagnosis of uncertain food allergy symptoms are lacking. We examined the diagnostic decision for a food allergy based on uncertain symptoms during an Open-OFC.

METHODS

We conducted an Open-OFC between August 2005 and April 2012 with 2271 cases who suspected as allergic to hen's eggs, cow's milk, or wheat. For the primary diagnosis, Open-OFCs with obvious symptoms were classified as "positive," no symptoms as "negative," and uncertain, indeterminate symptoms as "uncertain." We encouraged the children in the uncertain group to consume the causative foods at home more than twice; if any definitive symptoms were induced, children were classified as "intolerant," and children without any symptoms were classified as "tolerant," for the final diagnosis.

RESULTS

We analyzed 454 uncertain cases excluding 781 positive cases and 1036 negative cases. The symptoms that occurred for the uncertain cases included slight abdominal pain, localized skin rash, and an isolated cough. Of these cases, 362 (79.7%) were considered tolerant at the final diagnosis. Of the intolerant children at the final diagnosis, the induced symptoms at home were not serious.

CONCLUSIONS

Monitoring of recurring symptoms following consumption of causative foods at home by patients with uncertain symptoms improves the diagnostic accuracy of an Open-OFC.

Anti-IgE treatment with oral immunotherapy in multifood allergic participants: a double-blind, randomised, controlled trial

BACKGROUND

Despite progress in single food oral immunotherapy (OIT), there is little evidence concerning the safety and efficacy of treating individuals with multiple food (multifood) allergies. We conducted a pilot study testing whether anti-IgE (omalizumab) combined with multifood OIT benefitted multifood allergic patients.

METHODS

In this blinded, phase 2 clinical trial conducted at Stanford University, 48 participants, aged 4-15 years, with multifood allergies validated by double-blind, placebo-controlled food challenges (DBPCFCs) to their offending foods were block randomized (3:1) to receive multifood OIT to 2-5 foods, together with omalizumab (n=36) or placebo (n=12). Omalizumab or placebo was administered subcutaneously for 16 weeks with OIT starting at week 8; omalizumab or placebo was stopped 20 weeks before exit DBPCFCs (week 36) to determine the primary endpoint: the proportion of participants who passed DBPCFCs to at least 2 of their offending foods. This completed trial is registered with ClinicalTrials.gov, .

FINDINGS

At week 36, a significantly greater proportion of the omalizumab (30/36, 83%) vs. placebo (4/12, 33%) participants passed DBPCFCs to 2 g protein for ≥ 2 of their offending foods (odds ratio (OR): 10, 95% confidence interval (CI): 1·8, 58·3, P=0·004). The same individuals also tolerated 4 g protein of ≥ 2 foods (secondary endpoint, P=0·004). A greater proportion of omalizumab (13/17, 77%) vs. placebo (0/5, 0%) participants passed a DBPCFC to 2 g protein for ≥ 4 of their offending foods (OR: 33, 95% CI: 1·9, ∞, P=0·01). All participants completed the study. There were no serious or severe (≥ grade 3) adverse events.

INTERPRETATION

In multifood allergic patients, omalizumab improves the efficacy of multifood OIT and enables safe and rapid desensitization.

FUNDING

NIH U19 AADCRC and Opportunity Fund, Sean N. Parker Center for Allergy and Asthma Research at Stanford University, Simons Foundation, Myra Reinhard Foundation, FARE Center of Excellence, Department of Pathology, and Department of Pediatrics, Stanford University.

Elevated total serum immunoglobulin E (>1000 IU/mL): implications?

Atopic eczema, allergic broncho-pulmonary aspergillosis, helminthic infections and rare primary immunodeficiencies are known to elevate total serum immunoglobulin E (IgE) above 1000 IU/mL. However, of 352 patients with IgE >1000 IU/mL seen in our hospital over a 5-year period, less than 50% had these conditions. Markedly elevated IgE levels in the rest of the patients were associated with asthma, allergic rhinitis and food allergy, instances where the test is of limited diagnostic utility.

Safety and feasibility of heated egg yolk challenge for children with egg allergies

BACKGROUND

Hen's egg allergy is a frequent cause of childhood food allergy. Egg yolk is used in various commonly consumed foods; if children with allergy to hen's egg could eat heated egg yolk, their quality of life (QOL) would improve. No reports exist regarding oral food challenges (OFCs) for heated egg yolk. We aimed to clarify whether pediatric patients allergic to hen's egg could consume heated egg yolk.

METHODS

Data from pediatric patients who had undergone OFCs for heated egg yolk were evaluated retrospectively.

RESULTS

Among 919 patients, positive OFC results were obtained in 17.0% of patients; seven presented with severe symptoms. Older age, high specific IgE value for ovomucoid, low total IgE levels, and history of anaphylaxis related to food other than hen's egg were risk factors for positive OFC results. Specific IgE values for egg white, ovomucoid, and egg yolk, indicative of a negative predictive value >95%, were 0.71, 0.41, and 0.17 kU_A /l, respectively. A specific IgE to ovomucoid levels of 100 kU_A /l predicted heated egg yolk-positive OFCs for 38.3% of patients. Among 763 patients with a negative OFC, seven (0.9%) reacted to heated egg yolk at home, and 756 (99.1%) consumed hen's egg yolk safely.

CONCLUSIONS

Most pediatric patients allergic to heated hen's egg safely consumed heated egg yolk. Heated egg yolk OFCs rarely provoked severe symptoms and may be recommended for improving the QOL of children with allergy to hen's egg.

IgE-associated allergic disorders: recent advances in etiology, diagnosis, and treatment

IgE-associated allergic diseases belong to the most common inflammatory conditions. Their clinical manifestation ranges from mild symptoms to life-threatening episodes. Often patients experience a reduction in physical and psychologic well-being and suffer from a decreased quality of life due to disease activity. The continuously rising number of people that are affected by an allergic condition indicates an urgent need for better diagnostics and more efficient treatment options. Recent progress in the understanding of pathophysiologic mechanisms underlying IgE-associated allergic disorders has led to the identification of novel therapeutic targets and the development of drug candidates that are currently under evaluation. In this review, we highlight studies and clinical trials, which have helped to gain further insight in the etiology of IgE-associated allergic conditions as well as advances in the development of diagnostic tools and therapeutic approaches recently published in Allergy (European Journal of Allergy and Clinical Immunology).

Development of a prediction model of severe reaction in boiled egg challenges

BACKGROUND

We have proposed a new scoring system (Anaphylaxis SCoring Aichi: ASCA) for a quantitative evaluation of the anaphylactic reaction that is observed in an oral food challenge (OFC). Furthermore, the TS/Pro (Total Score of ASCA/cumulative protein dose) can be a marker to represent the overall severity of a food allergy. We aimed to develop a prediction model for a severe allergic reaction that is provoked in a boiled egg white challenge.

METHODS

We used two separate datasets to develop and validate the prediction model, respectively. The development dataset included 198 OFCs, that tested positive. The validation dataset prospectively included 140 consecutive OFCs, irrespective of the result. A 'severe reaction' was defined as a TS/Pro higher than 31 (the median score of the development dataset). A multivariate logistic regression analysis was performed to identify the factors associated with a severe reaction and develop the prediction model.

RESULTS

The following four factors were independently associated with a severe reaction: ovomucoid specific IgE class (OM-sIgE: 0-6), aged 5 years or over, a complete avoidance of egg, and a total IgE < 1000 IU/mL. Based on these factors, we made a simple scoring prediction model. The model showed good discrimination in a receiver operating characteristic analysis; area under the curve (AUC) = 0.84 in development dataset, AUC = 0.85 in validation dataset. The prediction model significantly improved the AUC in both datasets compared to OM-sIgE alone.

CONCLUSIONS

This simple scoring prediction model was useful for avoiding risky OFC.

The component-specific to total IgE ratios do not improve peanut and hazelnut allergy diagnoses

BACKGROUND

Specific IgE measurement predicts the outcome of oral food challenges with considerable uncertainty when evaluating food allergy.

OBJECTIVE

Our aim was to assess whether accounting for the ratio of component- or allergen-specific to total IgE can improve this prediction.

METHODS

This multicenter study collected blood samples from children with suspected peanut or hazelnut allergy referred to allergy specialist clinics for food challenges. Specific IgE to peanuts, hazelnuts, and their components (Ara h 1, Ara h 2, Ara h 3, Ara h 8, Cor a 1, Cor a 8, Cor a 9, and Cor a 14) and total IgE levels were determined by using the ImmunoCAP-FEIA. Specific to total IgE ratios were compared with raw IgE levels in terms of discrimination and prediction.

RESULTS

Eighty-eight (43%) of 207 children with suspected peanut allergy and 44 (31%) of 142 children with suspected hazelnut allergy had symptoms during food challenge. Discrimination was similar for raw and ratio measures: areas under the curve of 0.93 for Ara h 2-specific IgE versus 0.92 for the Ara h 2-specific/total IgE ratio and 0.89 for Cor a 14-specific IgE versus 0.87 for the Cor a 14-specific/total IgE ratio. The probability for a positive peanut challenge with 0.35 kU/L Ara h 2-specific IgE was 16% when the total IgE level was greater than 500 kU/L compared with 51%/48% for low/medium total IgE levels (<100/100-500 kU/L). A positive hazelnut challenge with 0.35 kU/L Cor a 14-specific IgE was estimated in 7% when total IgE levels were high compared with 34%/32% with low/medium total IgE levels.

CONCLUSIONS

Raw Ara h 2- and Cor a 14-specific IgE levels were the best single predictors for pediatric peanut and hazelnut allergies, suggesting the omission of challenges at very high levels. Calculating ratio measures did not improve prediction in this population. However, estimation of individual probabilities for challenge outcomes could be supported by total IgE levels because high levels might indicate lower probabilities at a given component-specific IgE level.

Allergic reactions to milk appear sooner than reactions to hen's eggs: a retrospective study

BACKGROUND

Oral food challenge test doses are recommended to be performed at least 20 min apart; however, the times of symptom provocation from the start of the oral food challenge have never been compared between different foods. In this study, the durations from the start of the oral food challenge to symptom development in children with egg or milk allergy were compared.

METHODS

Thirty-eight and 74 children who had previously passed oral food challenges to 96 g of yogurt and pumpkin cake containing ¼ whole egg underwent oral food challenges with 200 mL raw cow's milk and 1 whole scrambled egg, respectively; of these, 15/38 and 33/74 children had a reaction.

RESULTS

The median ages of patients with a positive challenge were 5.8 and 5.1 years for milk and eggs, respectively. The median times for the first symptom occurrence were 20 min (range, 5-55 min) and 50 min (5-480 min), respectively (p = 0.009). The first symptoms developed within 30, 60, and 90 min in 12/15 (80 %), 15/15 (100 %), and 15/15 (100 %) children with milk allergies, and in 10/33 (30.3 %), 20/33 (60.6 %), and 26/33 (78.8 %) children with egg allergies, respectively. The median times of peak symptoms were 50 min (10-210 min) and 120 min (30-560 min) (p = 0.001), and those of symptom disappearance were 90 min (30-240 min) and 180 min (80-700 min) for milk and eggs (p = 0.002), respectively.

DISCUSSION

Based on the results of our study, symptoms developed within 30 min for only a subset of patients for eggs, and may even take upwards of 60 min to develop. The times of symptom disappearance were 90 min and 180 min for milk and eggs, respectively, indicating that egg-allergic patients should be observed for a longer period time than milk-allergic patients.

CONCLUSIONS

Allergic reactions induced by milk appeared and disappeared sooner than those induced by eggs.

Update on food allergy

Food allergies are a global health issue with increasing prevalence. Allergic reactions can range from mild local symptoms to severe anaphylactic reactions. Significant progress has been made in diagnostic tools such as component-resolved diagnostics and its impact on risk stratification as well as in therapeutic approaches including biologicals. However, a cure for food allergy has not yet been achieved and patients and their families are forced to alter eating habits and social engagements, impacting their quality of life. New technologies and improved in vitro and in vivo models will advance our knowledge of the pathogenesis of food allergies and multicenter-multinational cohort studies will elucidate interactions between genetic background, lifestyle, and environmental factors. This review focuses on new insights and developments in the field of food allergy and summarizes recently published articles.