Positive Oral Food Challenge Research Articles

The Efficacy and Safety of Stepwise Oral Food Challenge in Children with Cow’s Milk Allergy

Plain Language SummaryStepwise oral food challenge (OFC) tests begin with low doses of allergens, progressing to full doses. This is one of the strategies used to avoid anaphylactic reactions to the reintroduction of allergens. We previously reported the safety and efficacy of hen egg OFC. In this study, we discuss it for cow’s milk (CM) allergy. We included 927 children (median age, 3.2 years) who underwent CM-OFC between 2017 and 2021. The target challenge dose was classified as low (<10 mL), middle (≥10 mL but <100 mL), or full. When the participants reacted to low doses, they underwent very low-dose OFC using baked milk or <1 mL of CM. Positive reactions developed in 210 cases (22.7%), including 69 anaphylactic reactions (7.4%). A lower target dose resulted in more positive OFC results and anaphylaxis. Multivariate analysis indicated that only in low-dose OFCs, higher CM-specific IgE (CM-sIgE) levels, younger age, and complete CM elimination were associated with positive OFC results. Food ladders, an approach to reintroduce allergens, are becoming increasingly popular. Although we believe that OFC is a safer strategy to reintroduce CM to children with CM allergy, our CM-OFCs appeared to develop more anaphylactic reactions than milk ladders. The stepwise OFC reintroduced small amounts of CM, even in cases with high CM-sIgE levels or a history of anaphylaxis. Performing CM-OFC at a younger age, preferably from infancy, with very low doses, similar to milk ladders, may facilitate the safe reintroduction of CM.

Poppy Seed Allergy: Molecular Diagnosis and Cross-Reactivity With Tree Nuts

BackgroundPoppy seed (PS) can be a cause of severe allergic reactions, especially in individuals with concurrent allergy to tree nuts and other seeds, but diagnostic criteria and sensitization patterns are lacking. ObjectiveTo assess the role of PS extract and individual allergens in diagnosing PS allergy and their cross-reactivities with tree nuts and buckwheat. MethodsOur retrospective study included 36 PS-sensitized patients; 10 with positive and 26 with a negative oral food challenge (OFC). We identified individual PS allergens and compared the diagnostic performance of sIgE to PS extract to its allergens. Cross-reactivities between PS and related allergens from other seeds was assessed by competitive ELISA. ResultsWe identified four novel PS allergens: Pap s 1 (vicilin), Pap s 1 (27-424) (α-hairpinin), Pap s 2 (legumin), and Pap s 3 (small hydrophilic seed protein). Positive OFC correlated with higher PS-sIgE levels and elevated sIgE levels for the PS allergens, except for Pap s 3. PS and α-hairpinin-sIgE effectively differentiated allergic from tolerant patients, with AUC values of 0.95 and 0.94. PS-sIgE >10.00 kUA/L exhibited 90% sensitivity and 73% specificity, while α-hairpinin -sIgE >2.60 kUA/L showed 100% sensitivity and 77% specificity. PS vicilin and legumin highly cross-reacted with hazelnut and buckwheat homologues, while α-hairpinin-sIgE cross-reacted with the related almond allergen. ConclusionsThis is the most extensive study on poppy seed allergy to date. Poppy seed and α-hairpinin-sIgE are highly sensitive indicators of clinical reactivity to poppy seeds, while vicilin and legumin-sIgE contribute to concurrent sensitization to hazelnut and buckwheat.

Role of serum-specific immunoglobulin E in egg allergy: a comprehensive study of Portuguese pediatric patients.

Food allergies represent a growing public health concern, particularly among children. This study aims to examine egg allergy in pediatric patients and analyze the value of serum-specific immunoglobulin E (sIgE) levels as predictive biomarkers for oral food challenge (OFC) outcomes. Retrospective study, involving pediatric patients with suspected IgE-mediated egg allergy, conducted at a tertiary hospital. Data from 176 pediatric patients were analyzed, revealing a higher male prevalence (59.1%). Most cases (40.3%) presented symptoms in the first year of life, predominantly mucocutaneous symptoms (46%). OFC results varied across various forms of egg presentation, with cooked egg being the most frequently tested food. Positive OFCs were observed in 14.6% (n = 36) of cases. The study identified specific egg protein biomarkers for positive OFC, with ovalbumin for raw egg (sIgE > 1.28 KUA/L; area under the curve [AUC] = 0.917; sensitivity [S] 100%; and specificity [Sp] 92%), ovomucoid for cooked egg (sIgE > 0.99 KUA/L; AUC = 0.788, 95%; S: 79%; and Sp: 74%), and ovomucoid for baked egg (sIgE> 4.63 KUA/L; AUC = 0.870; S: 80%; and Sp: 85%) showing predictive capacities. The findings underscore the importance of considering various forms of egg presentation in the diagnosis and management of egg allergy. The findings highlight the valuable discriminatory capacity and provided reliable biomarkers, such as ovalbumin for raw egg and ovomucoid for cooked and baked egg in risk assessment, aiding in predicting OFC outcomes and helping clinicians to make informed decisions in diagnosing and managing egg allergies, thus improving patient care and quality of life.

Management of food allergy based on oral food challenge.

Food allergy is a growing health problem that affects both patients and society in multiple ways. Despite the emergence of novel diagnostic tools, such as component-resolved diagnostics (CRD) and basophil activation tests (BAT), oral food challenge (OFC) still plays an indispensable role in the management of food allergies. This review aimed to highlight the indications and safety concerns of conducting an OFC and to provide insights into post-OFC management based on recent findings. Standardized OFC protocols have regional diversification, especially in Japan and Western countries. Recent studies suggested that the interval between doses should be at least more than an hour. Furthermore, applying a stepwise method tailored to the patient's specific immunoglobulin E level and history of anaphylaxis seems to mitigate these risks. Recent surveys have shown that, following a positive OFC, options other than strict avoidance are also selected. OFC serves diverse purposes, yet the risks it carries warrant caution. The stepwise protocol appears promising for its safety. Subthreshold consumption following OFC shows potential; however, further research on its efficacy and safety is required. Management following OFC should be tailored and well discussed between clinicians and patients.

Validation of the NUT CRACKER Diagnostic Algorithm and Prediction for Cashew and Pistachio Co-Allergy

BackgroundDue to the high cross sensitization among tree nuts, the NUT CRACKER study proposed a diagnostic algorithm to minimize the number of required oral food challenges (OFC). ObjectiveThe objective of this study was to validate the algorithm for cashew and pistachio allergy and determine markers for allergic severity. MethodsPatients (n=125) aged 7.9 (5.9-11.2) years (median (IQR)) with suspected tree nut allergy were evaluated prospectively with decision tree points based on skin prick test (SPT), basophil activation test (BAT) and knowledge of the coincidence of allergies. Validation of allergic status was determined by OFC. Markers of clinical severity were evaluated using the combined original and prospective cohort (n=187) in relationship to SPT, BAT and Ana o 3-sIgE. ResultsReactivity to cashew in SPT, BAT and Ana o 3-sIgE and the incidence of abdominal pain upon challenge were significantly higher in dual-allergic cashew/pistachio patients (n=82) vs single cashew allergy (n=18) (p=0.001). All three diagnostic tests showed significant inverse correlation with log10 reaction doses for positive cashew OFC. The algorithm reduced overall the total number of OFCs by 72.0% with a PPV and NPV of 93.0% and 99.0%, respectively. Cashew false positives were observed primarily in hazelnut allergic patients (p=0.026). In this population, Ana o 3-sIgE could diagnose cashew allergy with a sensitivity over 90%, and a specificity over 95%. ConclusionThe NUT CRACKER diagnostic algorithm was validated and reduced the number of diagnostic OFCs required. Markers for severity phenotypes may guide oral immunotherapy protocols, improving the risk/benefit ratio for patients.

Clinical Features of Quail Egg Ingestion in Patients with Acquired Tolerance to Hen Eggs: A Case Series Study

Introduction: Patients with hen’s egg allergy are often instructed to avoid consuming other avian eggs, such as quail eggs. However, it is unclear whether patients with an acquired tolerance to hen eggs continue to avoid consuming quail eggs. This study aimed to evaluate the clinical features of quail egg ingestion. Methods: This prospective case series included children aged ≥1 year with hen’s egg allergy who were recruited between October 2019 and February 2021 in our hospital. We conducted an oral food challenge (OFC) with three boiled quail eggs to evaluate the clinical features of quail egg ingestion in patients with acquired tolerance to hen eggs. The primary outcome was a positive OFC after ingesting three quail eggs. Secondary outcomes were cross-antigenicity between hen and quail eggs observed through the skin prick test (SPT) and pattern of quail egg allergy, comprising the onset of reaction, and severity. The correlation between the diameters of the wheals with SPT in hen and quail eggs was evaluated using the Pearson product-moment correlation coefficient. Results: A total of 62 patients underwent the quail egg OFC. The median (interquartile range) age of the participants was 3 (2–5) years. Thirty-three (53%) patients had a history of anaphylaxis due to hen eggs. The median total immunoglobulin E (IgE) level in patients who underwent the OFC with half a heated whole hen’s egg was 271 (98–593) IU/mL. The median specific IgE level in egg white and ovomucoid was 9.7 (3.2–21.5) and 4.4 (1.3–6.9) UA/mL, respectively. The quail egg OFC results revealed that none of the 59 patients who ate the three quail eggs completely had an allergic reaction. The SPT-positive and SPT-negative rates in raw and boiled hen and quail egg whites were both correlated. The diameters of wheals with SPT in raw hen and quail egg whites and yolks were positively correlated. Conclusion: Patients with an acquired tolerance to hen eggs may not be required to avoid consuming quail eggs.

Relationship between the diagnosis of food protein-induced enterocolitis syndrome and postemetic procalcitonin levels.

There are no reports on the relationship between food protein-induced enterocolitis syndrome (FPIES) diagnosis and procalcitonin levels. Our study sought to demonstrate a correlation between the presence or absence and severity of FPIES symptoms and postemetic procalcitonin levels. The subjects were 53 patients with FPIES (44 with hen's egg allergy, 4 with milk allergy, 4 with wheat allergy, and 3 with soy allergy), who collectively underwent a total of 75 oral food challenges (OFCs). Procalcitonin levels at 5 hours after antigen ingestion were compared between patients with a positive OFC result and those with a negative OFC result and between patients who experienced mild or moderate events and those who experienced severe events. At 5 hours after ingestion of the causative food, the median procalcitonin levels in patients with a negative OFC result, patients who experienced a mild or moderate event, and patients who experienced a severe event were 0.02, 0.03, and 0.16 ng/mL, respectively. The procalcitonin level was significantly higher in the groups with a positive OFC result than in the groups with a negative OFC result (P< .001), and it was significantly higher in those who experienced severe events than in those who experienced mild or moderate events (P= .012). Measurement of procalcitonin levels has the potential to provide a quantitative and objective assessment of FPIES diagnosis and severity.

Outcomes and factors associated with tolerance in infants with non-IgE-mediated cow's milk allergy with gastrointestinal manifestations

ObjectivesTo evaluate outcomes of oral food challenge (OFC) test to assess tolerance in infants with non-IgE-mediated cow's milk allergy (CMA) with gastrointestinal manifestations and explore clinical data predictive of these outcomes. MethodsSingle-center retrospective study including infants (age < 12 months) who were referred for CMA between 2000 and 2018 and underwent OFC on follow-up. A univariate logistic regression test was performed to evaluate variables associated with the outcomes of the follow-up OFC test. ResultsEighty-two patients were included, 50% were male. Eighteen patients had a positive OFC test (22%). Most patients had presented with hematochezia (77%). The median age of symptom onset was 30 days. Two-thirds of the patients were on appropriate infant formula (extensively hydrolyzed or amino acid-based formula), exclusively or in association with breastfeeding. The median time on an elimination diet before the OFC test was 8 months (Q1 6 – Q3 11 months). All cases with positive follow-up OFC tests (n = 18) had been exposed to cow's milk-based formula before the first clinical manifestation of CMA. Five out of eight cases with Food Protein-Induced Enterocolitis Syndrome (FPIES) had positive OFC tests. Exposure to cow's milk-based formula before diagnosis, a history of other food allergies, hematochezia and diarrhea were predictors of a positive OFC test. ConclusionsIn infants with non-IgE-mediated CMPA with gastrointestinal manifestations, the use of cow's milk-based formula, a history of other food allergies, and hematochezia and diarrhea upon initial presentation were associated factors for the later achievement of tolerance.

Challenge-verified thresholds for allergens mandatory for labeling: How little is too much for the most sensitive patient?

It is mandatory to label food products with the 14 main allergens in the EU. Reasonable allergen labeling requires knowledge of population-based thresholds derived from food challenges. The aim of this study was to evaluate the threshold-distribution in clinically verified food allergic patients for allergens mandatory for labeling. All positive open oral food challenges and double-blind placebo-controlled food challenges (DBPCFC) performed at the Allergy Center, Odense University Hospital, Denmark (2000-2022) were included. For each included challenge, the cumulative threshold (LOAEL) was obtained and NOAEL estimated. Data were modelled as an interval censored log-normal distribution. Overall, 38 of all 2612 challenges (1.5%) in 1229 patients (717 male, 986 children) reacted to <5 mg protein. The majority of the most sensitive patients reacted with a Sampson severity score of 2-3. Using interval censored log-normal models only five groups (hens´ egg, fish, peanut, milk, tree-nuts) elicited reactions after ingestion of 0.5 mg protein and in low frequencies of the population. Hen's egg was the most potent allergen, with reactivity to <0.5 mg protein in 0.24% [0.13-0.44%] of egg allergic patients while the estimated fraction of allergic patients reacting to a eliciting dose on 0.5 mg protein for most other allergens were below 0.04%. Our data demonstrates that the majority of food allergic patients as expected tolerating traces of allergenic foods without developing severe allergic symptoms and signs. Hen's egg appears to be the food most likely to elicit reactions in the most sensitive individuals at very low doses.

Oral food challenge in children with contact urticaria in reaction to cow's milk.

To evaluate the relationship between the occurrence of contact urticaria in reaction to cow's milk in infants and the diagnosis of cow's milk allergy (CMA) established by supervised oral food challenge. In this cross-sectional study, we identified 184 children who had undergone 221 oral food challenge (OFC) at a CMA reference center between July 2015 and August 2019. Of these, 23 (12.5%) had a history of contact urticaria to cow's milk and underwent a total of 30 OFC. Baked cow's milk OFC were excluded, and 21 children were included in the study. All data from clinical history and allergy tests (serum-specific IgE dosages and skin prick test [SPT] with reconstituted cow's milk formula) were recorded on standardized forms. The challenge was conducted with reconstituted cow's milk formula in increasing volumes every 15-20 min. 24 OFC were performed; 13/24 (54.2%) for diagnostic purpose and 11/24 (45.8%) to evaluate cow's milk tolerance. Allergy tests were positive in 14 patients (87.5%). Positive oral challenge outcomes were identified in 7/24. One patient had a late flare of atopic dermatitis and five children presented with immediate urticaria (two generalized urticaria and three perioral urticaria). The median papule diameter was 6.5 mm in patients with a positive OFC and 3.75 mm in the negative group (P = 0.02). The occurrence of contact urticaria might be the only manifestation among infants sensitized to cow's milk with tolerance to oral ingestion. Reactions due to oral challenge were related to a larger wheal diameter on the SPT.

Sensitisation to peach allergen Pru p 7 is associated with severe clinical symptoms in a Spanish population.

Pru p 7 has been reported as a major allergen in peach allergy, associated with severe clinical symptoms and related to IgE sensitisation to cypress pollen. The main objective of this study was to prospectively evaluate the frequency of sensitisation to Pru p 7 and its clinical relevance amongst pediatric patients with peach allergy in Madrid (Spain). Patients with a history of IgE-mediated symptoms (oral allergy syndrome, urticaria/angioedema, rhinoconjunctivitis/asthma, gastrointestinal symptoms, or anaphylaxis) occurring within 2 h after peach intake or contact were prospectively recruited from February 2020 to September 2021. Skin tests, sIgE by ImmunoCAP® (Pru p 1, Pru p 3, Pru p 4, Pru p 7, and Cupressus arizonica) and oral food challenge (OFC) were performed. The study was approved by the local Ethics Committee (PI-4513). Ninety-two patients were included (53.3% male); median age, 10 (IQR 6.0-14.75) years. Seventy-four (80.4%) patients had a reaction after ingestion of fresh peach (25.0% from peel, 23.9% from pulp, and 44.6% from both). Fifteen (16.3%) patients were sensitised to Pru p 7. Upper airway symptoms, anaphylaxis, and grade 2 reactions were statistically more frequent in patients sensitised to Pru p 7. Seven (7.9%) patients presented with exercise as a cofactor, four of whom were sensitised to Pru p 7 (p = .001). Patients sensitised to Pru p 7 were significantly more likely to have a positive OFC result than patients who were not (p = .008). Four patients who reacted to peach at OFC were sensitised to Pru p 7. Specific IgE against Cupressus arizonica pollen was positive in 25 (62.5%) patients. Pru p 7 sensitisation was observed in 16.3% of our population and was related to severe reactions, upper airway symptoms, anaphylaxis, and the presence of an eliciting cofactor.

Sesame eliciting and safe doses in a large sesame allergic population.

Sesame is a significant food allergen causing severe and even fatal reactions. Given its increasing prevalence in western diet, sesame is listed as an allergenic food requiring labeling in the United States and EU. However, data on the population reaction doses to sesame are limited. All sesame oral food challenges (OFCs), performed either for diagnosis or for threshold identification before the beginning of sesame oral immunotherapy (OIT) between November 2011 and July 2021 in Shamir medical center were analyzed for reaction threshold distribution. Safe-dose challenges with 90-120 min intervals were also analyzed. Two hundred and fifty patients underwent 338 positive OFCs, and additional 158 safe-dose OFCs were performed. The discrete and cumulative protein amounts estimated to elicit an objective reaction in 1% (ED01) of the entire cohort (n = 250) were 0.8 mg (range 0.3-6.3) and 0.7 mg (range 0.1-7.1), respectively, and those for 5% of the population (ED05) were 3.4 mg (range 1.2-20.6) and 4.5 mg (range 1.2-28.8), respectively. Safe-dose OFCs showed similar values of ED01 (0.8, 0.4-7.5 mg) and ED05 (3.4, 1.2-22.9 mg). While doses of ≤1 mg sesame protein elicited oral pruritus in 11.6% of the patients, no objective reaction was documented to this amount in any of the challenges, including safe-dose OFCs. This study provides data on sesame reaction threshold distribution in the largest population of allergic patients studied, with no right or left censored data, and with validation using a safe-dose OFC. It further supports the current methods for ED determination as appropriate for establishing safety precautions for the food industry.

Transepidermal water loss rises before food anaphylaxis and predicts food challenge outcomes.

Food allergy (FA) is a growing health problem requiring physiologic confirmation via the oral food challenge (OFC). Many OFCs result in clinical anaphylaxis, causing discomfort and risk while limiting OFC utility. Transepidermal water loss (TEWL) measurement provides a potential solution to detect food anaphylaxis in real time prior to clinical symptoms. We evaluated whether TEWL changes during an OFC could predict anaphylaxis onset. Physicians and nurses blind to TEWL results conducted and adjudicated the results of all 209 OFCs in this study. A study coordinator measured TEWL throughout the OFC and had no input on OFC conduct. TEWL was measured two ways in two separate groups. First, TEWL was measured using static, discrete measurements. Second, TEWL was measured using continuous monitoring. Participants who consented gave blood before and after OFCs for biomarker analyses. TEWL rose significantly (2.93 g/m2/h) during reactions and did not rise during non-reacting OFCs (-1.00 g/m2/h). Systemic increases in tryptase and interleukin-3 were also detected during reactions, providing supporting biochemical evidence of anaphylaxis. The TEWL rise occurred 48 minutes earlier than clinically evident anaphylaxis. Continuous monitoring detected a significant rise in TEWL that presaged positive OFCs, but no rise was seen in OFCs with no reaction, providing high predictive specificity (96%) for anaphylaxis against non-reactions 38 minutes prior to anaphylaxis. During OFCs, a TEWL rise anticipates a positive clinical challenge. TEWL presents a novel monitoring modality that may predict food anaphylaxis and facilitate improvements in OFC safety and tolerability.

The combination of Ara h 2-sIgE and basophil activation test could be an alternative to oral food challenge in cases of suspected peanut allergy.

Most children with peanut sensitisation do not have a clinical peanut allergy (PA). Oral food challenge (OFC) is then necessary to diagnose PA and assess the reactive dose of the allergen. However, OFC is laborious to perform, expensive and stressful. We evaluated whether in vitro tests, such as basophil activation test (BAT), allergen-specific IgE (sIgE) and their combination, could be used to replace OFC for the diagnosis of PA in children. Ninety-one patients aged 6 months to 18 years with suspected PA were prospectively recruited. These patients then underwent an OFC to assess PA. Whole peanut-sIgE, Ara h 2-sIgE, Ara h 8-sIgE and %CD63+ basophils (CCR3+ /SCClow ) to peanut measured by BAT were investigated for PA diagnosis. Forty-one patients had a positive peanut OFC, and the remaining 50 were only sensitised. All patients with Ara h 2-sIgE >7 kUA /L were allergic to peanut. A threshold of 6% for activated basophils yielded a sensitivity of 95% and a specificity of 54%. All patients with Ara h 2-sIgE ≤7 kUA /L and BAT ≤6% (n = 22) had a negative OFC except for one who presented an oral syndrome due to PR-10 sensitisation. We have shown that Ara h 2-sIgE >7 kUA/L is a discriminating threshold for the diagnosis of PA. Furthermore, when Ara h 2-sIgE ≤7 kUA/L and BAT ≤6%, patients do not need to adjust their diet and, thus, do not need an OFC.

The role of basophil activation test and component-resolved diagnostics in the workup of egg allergy in children at low risk for severe allergic reactions: A real-life study.

The gold standard for diagnosing egg allergy in children is the oral food challenge (OFC). However, OFCs are time-consuming and risky procedures. Our study aimed to evaluate the utility of the basophil activation test (BAT) and component-resolved diagnostic in the diagnostic workup of children with egg allergy. Overall, 86 children aged 6 months to 17 years, suspected of egg allergy, underwent OFC with boiled egg according to international standardized protocols. BAT and specific immunoglobulin E (sIgE) testing to component egg proteins (Gal d 1-4) were also performed. Of the 22 children who reacted to boiled egg, only one experienced anaphylaxis during the challenge. BAT was performed in samples obtained by 75 of the 86 patients of our cohort. Egg white and yolk protein extracts induced CD63 upregulation in the egg-allergic (EA) children compared with sensitized children that tolerated boiled egg (we registered an overall mean of CD63 expression in the EA population of 44.4% [SD 34.1] for egg white and 34.7% [SD 31.3] for egg yolk vs. 12.5% [SD 19.1] and 10.0% [SD 16.0] in sensitized children). BAT could discriminate between true egg allergy and egg sensitization in our population. As a second-line diagnostic step, the positivity of BAT for egg white or Gal d 1-sIgE resulted in a 40.9% OFC reduction, especially for those with a positive outcome. The BAT may be implemented in the diagnostic workup of egg allergy in children and, in a stepwise approach, separately or combined with Gal d 1-sIgE, may predict the allergic status and reduce the number of positive OFCs in children with egg allergy at low risk for severe reactions.

Sesame allergy in children: New insights into diagnosis and management.

Sesame is a potentially potent allergen that can trigger skin, gastrointestinal, and respiratory tract symptoms, and anaphylaxis. Only 20% to 30% of sesame-allergic children develop tolerance. The prevalence of sesame allergy depends on local diets and ranges from 0.1% to 0.9%. A high risk of accidental exposure to sesame has resulted in mandatory food labeling in many countries. More than half of patients with sesame allergy are also allergic to peanut/tree nuts. Serum-specific IgE testing with a quantitative Ses i 1 component can be performed safely and has higher clinical specificity and better positive predictive value for oral food challenge (OFC) than whole sesame extract or skin prick testing (SPT). Compared with SPT or OFC, in vitro Ses i 1 testing requires no special techniques and carries no risk of reactions. Diagnosis of suspected sesame allergy begins with a thorough history and physical examination. A positive sesame extract test (≥0.1 kUA /L) should prompt further testing. In patients with a high probability of reacting, results of component testing may facilitate a decision about performing an OFC. In a Japanese study of OFC and Ses i 1, there was a 5% probability of a positive OFC with Ses i 1 sIgE levels <0.13 kUA /L, and a 50% probability of a positive OFC with levels >32.0 kUA /L. Most patients could safely consume sesame if sIgE levels were <0.13 kUA /L. Ses i 1 testing can be used to guide appropriate management (avoidance, emergency medication, and oral immunotherapy).

Low-Dose Oral Challenge Test in Pediatric Patients With Peanut Allergy: Tolerance Assessment of a Trace 5 mg Peanut Test After Symptom Induction With a 500 mg Test.

Introduction Peanut allergy (PA) represents a significant public health concern, particularly prevalent in Western countries.Children at high risk for PA may undergo a low-dose oral food challenge (OFC). However, if the result is positive, complete elimination of peanuts from the diet is recommended, and further trace OFC is typically not performed. Material and methods This cross-sectional study retrospectively examined the rate of positive peanut OFC with a total peanut load of 5 mg in children who tested positive with a total peanut load of 500 mg. Patient information was gathered from medical records. The primary endpoint was the rate at which children who tested positive in the OFC with 500 mg of peanut butter also tested positive with 5 mg of peanut butter equivalent. Results Among 32 children who underwent an OFC with a total peanut load of 500 mg, two were excluded for not meeting the criteria. Among the remaining 30 children, 14 (46.7%) had a positive 500 mg peanut OFC test, and three (10%) experienced an anaphylactic reaction. Those who tested positive for the OFC had higher peanut-specific and Ara h2-specific immunoglobulin E (IgE) antibodies. An OFC with 5 mg of peanuts performed on 10 of the 14 patients who tested positive for 500 mg of peanuts showed no positive results. Conclusion The results of this study suggest that children with severe PA who exhibit positive symptoms to a total peanut load of 500 mg can tolerate a 5 mg dose of peanuts and should be considered for an OFC.

The Combination of Binding Avidity of Ovomucoid-Specific IgE Antibody and Specific IgG4 Antibody Can Predict Positive Outcomes of Oral Food Challenges during Stepwise Slow Oral Immunotherapy in Children with Hen's Egg Allergy.

To increase the prediction accuracy of positive oral food challenge (OFC) outcomes during stepwise slow oral immunotherapy (SS-OIT) in children with a hen's egg (HE) allergy, we evaluated the predictive value of the combination of antigen-specific IgE (sIgE) with antigen binding avidity and sIgG4 values. Sixty-three children with HE allergy undergoing SS-OIT were subjected to repeated OFCs with HE. We measured the ovomucoid (OVM)-sIgE by ImmunoCAP or densely carboxylated protein (DCP) microarray, sIgG4 by DCP microarray, and the binding avidity of OVM-sIgE defined as the level of 1/IC50 (nM) measured by competitive binding inhibition assays. The OFC was positive in 37 (59%) patients undergoing SS-OIT. Significant differences in DCP-OVM-sIgE, CAP-OVM-sIgE, I/IC50, DCP-OVM-sIgG4, the multiplication products of DCP-OVM-sIgE, and the binding avidity of DCP-OVM-sIgE (DCP-OVM-sIgE/IC50) and DCP-OVM-sIgE/sIgG4 were compared between the negative and positive groups (p < 0.01). Among them, the variable with the greatest area under the receiver operating characteristic curve was DCP-OVM-sIgE/IC50 (0.84), followed by DCP-OVM-sIgE/sIgG4 (0.81). DCP-OVM-sIgE/IC50 and DCP-OVM-sIgE/sIgG4 are potentially useful markers for the prediction of positive OFCs during HE-SS-OIT and may allow proper evaluation of the current allergic status in the healing process during HE-SS-OIT.

Peanut thresholds in peanut-allergic children are related to dietary composition.

There is no clear explanation for the large variation in threshold levels among peanut-allergic children. We hypothesized that diet composition can partly explain this variation in thresholds, as nutrients and foods influence the intestinal barrier function and microbiota. to explore the relationship between the threshold levels for peanut and nutritional intake and gut microbial composition in peanut-allergic children. In this explorative cross-sectional study the cumulative threshold levels for peanut were determined by oral food challenge tests. Data on nutrients and foods consumed were obtained from 3-day food diaries. Microbial composition of faeces and saliva were determined by molecular microbiota detection technique. Multivariable linear regression analysis and multiple logistic regression were used to explore the associations, adjusted for energy and senitization. Sixty-five children were included, of whom 32 (49%) (median age 50 months, IQR 28.0-96.5) had a positive oral food challenge. Significant positive associations were found between the intake of total carbohydrates, vitamin A and cumulative threshold levels for peanut, while significant negative associations were found for long-chain polyunsaturated fatty acids, linoleic acid and omega-6 fatty acids. No associations were found between threshold levels and microbial composition of faeces and saliva. However, a significant higher abundance of Proteobacteria and Bacteroidetes in saliva (p = 0.011 and 0.04, respectively) and of Proteobacteria in faeces (p = 0.003) were found in children with a positive peanut challenge compared to children with a negative peanut challenge. As a novel concept, this study showed that dietary composition is related to threshold levels for peanut.

Diagnostic accuracy of atopy patch test in children with cow’s milk allergy

BackgroundThe accuracy of an atopy patch test (APT) for fresh cow’s milk allergy is controversial. Few studies have focused on commercial extract solutions. We aimed to evaluate the diagnostic performance of the APT in cow’s milk allergic children using fresh cow’s milk and commercial extracts of cow’s milk and its components including casein, α-lactalbumin, and β-lactoglobulin.MethodsA prospective study was carried out in children with a history of cow’s milk allergy. Children underwent the skin prick test (SPT) and APT with fresh cow’s milk, powdered cow’s milk, and commercial extracts of cow’s milk, casein, α-lactalbumin, and β-lactoglobulin. Oral food challenge (OFC) was confirmed in all children.ResultsA total of 37 patients participated (mean age 13.14 ± 7.26 months). Only 5 (13.51%) patients had positive OFC to cow’s milk. The sensitivity of the APT using fresh cow’s milk was 40%, specificity was 65.6%, PPV was 15.4%, and NPV was 87.5%. The sensitivity of the APT using powdered cow’s milk was 40%, 60.7% for specificity, 15.4% for PPV, and 58% for NPV. The sensitivity and PPV of the APT using commercial solutions of cow’s milk, casein, α-lactalbumin, and β-lactoglobulin were zero. The specificities were 90.6%, 93.8%, 100%, and 100% for α-lactalbumin, cow’s milk, casein, and β-lactoglobulin, respectively.ConclusionsAPT using commercial solutions showed higher specificity than fresh milk. The specificity increased using a protein component allergen.