Parental Intentions Regarding Introduction of Common Food Allergens During Complimentary Feeding
Food allergy affects 5-6% of Irish children with 3-6% of preschool children affected. Common food allergens in preschool children are milk, egg and peanut while peanut, tree-nut, fish and shellfish allergies are more common in older children1. Recent studies such as LEAP2 and EAT3 reported that regular consumption of common allergy associated foods early in the complementary feeding period resulted in a protective effect on the development of food allergy2,3. Current guidelines recommend that solid foods should be introduced into the infant diet around 6 months of age, including the common allergenic foods, and these foods should be continued on a regular basis. For children at a higher risk of developing food allergy, the early introduction (from 4 months of age) of egg and peanut may be beneficial.
Survey of Commercial Food Products for Detection of Walnut ( Juglans regia) by Two ELISA Methods and Real Time PCR
Labeling of food allergens in accordance with legal regulations is important to protect the health of allergic consumers. The requirements for detecting allergens in foods involve adequate specificity and sensitivity to identify very small amounts of the target allergens in complex food matrices and processed foods. In this work, one hundred commercial samples were analyzed for walnut detection using three different methods: a sandwich enzyme-linked immunosorbent assay (ELISA) kit based on polyclonal antibodies, a direct ELISA using a recombinant multimeric scFv, and a real time PCR. The most sensitive method was real time PCR followed by sandwich ELISA kit and multimeric scFv ELISA. There was agreement between the three methods for walnut detection in commercial products, except for some heat-treated samples or those that contained pecan. The walnut ELISA kit was less affected by sample processing than was the multimeric scFv ELISA, but there was cross-reactivity with pecan, producing some false positives that must be confirmed by real time PCR. According to the results obtained, 7.0 to 12.6% of samples (depending on the analytical method) contained walnut but did not declare it, confirming there is a risk for allergic consumers. Moreover, there was one sample (3.7%) labelled as containing walnut but that tested negative for this tree nut. Genetic and immunoenzymatic techniques offer complementary approaches to develop a reliable verification for walnut allergen labeling.
https://doi.org/10.3390/foods10020440
Treatment with lipid transfer protein sublingual immunotherapy: slowing down new sensitizations
Food allergy (FA) is a potentially life-threatening condition, food allergen immunotherapy, targeting the underlying mechanisms, is a potentially curative strategy in FA. A 46-year-old woman had an episode of facial angioedema and urticaria after mandarin ingestion and other episode of urticaria, abdominal pain, and facial angioedema after eating hazelnuts and almonds 4 years ago and contact urticaria (CU) with the manipulation of the peach skin. Three years ago, she suffered a facial and glottis angioedema, generalized urticaria, vomiting, and abdominal pain 10-15 minutes after eating green beans. She was treated with intravenous corticosteroids and antihistamines and intramuscular epinephrine, with complete resolution within a few hours. She no longer consumed nuts, and she avoided vegetables or fruits that caused her symptoms. Prick-prick test were performed, being positive with lettuce, eggplant, and cabbage and negative for cauliflower and broccoli. Total IgE (UniCAP method, kU/L) was 39.3, specific IgE Prup3 lipid transfer protein (LTP), 3.9; specific IgE to peanut, peach, pear, lemon, almond, avocado, walnut, cherry, and green bean were also positive. We decided to try to stop the march of the LTP sensitizations. Sublingual immunotherapy with a peach extract quantified in 12 μg/mL of peach allergen Prup3 was then initiated without any adverse event, and she has good adherence to the treatment. After 1 year, single-blind oral challenge test with peach, mandarin, and aubergine, were performed up to a portion dose (approximately 100 g) with all good tolerances.
https://doi.org/10.5415/apallergy.2021.11.e6
Effect of deglycosylation on immunoreactivity and in vitro pepsin digestibility of major cashew (Anacardium occidentale L.) allergen, Ana o 1
Major cashew allergen, Ana o 1, was purified in its native form from cashew seeds and subjected to enzymatic deglycosylation using PNGase F to assess the potential role of N-glycans in immunoreactivity. Western and dot blotting with pooled human plasma containing anticashew IgE revealed that deglycosylation increased IgE-binding of Ana o 1. Removal of N-glycans may have exposed previously masked Ana o 1 epitopes. Purified glycosylated and deglycosylated Ana o 1 were also subjected to in vitro pepsin digestion at pH 3.0 for 2 hr. Both glycosylated and deglycosylated Ana o 1 remained stable and reactive with IgE antibodies following digestion. PRACTICAL APPLICATION: Understanding the role of glycosylation in Ana o 1 immunoreactivity may provide insight into the potential development of hypoallergenic cashews/cashew products for sensitive individuals in the future.
Inverse relation between structural flexibility and IgE reactivity of Cor a 1 hazelnut allergens
A major proportion of allergic reactions to hazelnuts (Corylus avellana) are caused by immunologic cross-reactivity of IgE antibodies to pathogenesis-related class 10 (PR-10) proteins. Intriguingly, the four known isoforms of the hazelnut PR-10 allergen Cor a 1, denoted as Cor a 1.0401-Cor a 1.0404, share sequence identities exceeding 97% but possess different immunologic properties. In this work we describe the NMR solution structures of these proteins and provide an in-depth study of their biophysical properties. Despite sharing highly similar three-dimensional structures, the four isoforms exhibit remarkable differences regarding structural flexibility, hydrogen bonding and thermal stability. Our experimental data reveal an inverse relation between structural flexibility and IgE-binding in ELISA experiments, with the most flexible isoform having the lowest IgE-binding potential, while the isoform with the most rigid backbone scaffold displays the highest immunologic reactivity. These results point towards a significant entropic contribution to the process of antibody binding.
https://doi.org/10.1038/s41598-021-83705-z
Component-Resolved Diagnosis of Hazelnut Allergy in Children
Hazelnuts commonly elicit allergic reactions starting from childhood and adolescence, with a rare resolution over time. The definite diagnosis of a hazelnut allergy relies on an oral food challenge. The role of component resolved diagnostics in reducing the need for oral food challenges in the diagnosis of hazelnut allergies is still debated. Therefore, three electronic databases were systematically searched for studies on the diagnostic accuracy of specific-IgE (sIgE) on hazelnut proteins for identifying children with a hazelnut allergy. Studies regarding IgE testing on at least one hazelnut allergen component in children whose final diagnosis was determined by oral food challenges or a suggestive history of serious symptoms due to a hazelnut allergy were included. Study quality was assessed by the Quality Assessment of Diagnostic Accuracy Studies-2 tool. Eight studies enrolling 757 children, were identified. Overall, sensitivity, specificity, area under the curve and diagnostic odd ratio of Cor a 1 sIgE were lower than those of Cor a 9 and Cor a 14 sIge. When the test results were positive, the post-test probability of a hazelnut allergy was 34% for Cor a 1 sIgE, 60% for Cor a9 sIgE and 73% for Cor a 14 sIgE. When the test results were negative, the post-test probability of a hazelnut allergy was 55% for Cor a 1 sIgE, 16% for Cor a9 sIgE and 14% for Cor a 14 sIgE. Measurement of IgE levels to Cor a 9 and Cor a 14 might have the potential to improve specificity in detecting clinically tolerant children among hazelnut-sensitized ones, reducing the need to perform oral food challenges.
https://doi.org/10.3390/nu13020640
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: 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 based on ImmunoCAP-ISAC (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 (LAD2) sensitized with patients' plasma were stimulated with peanut or controls and assessed by flow cytometry.
Results: SA to peanut (p<0.001), Ara h 1 (p=0.004), Ara h 2 (p<0.001), Ara h 3 (p=0.02) and Ara h 6 (p<0.001) and the avidity of peanut-sIgE (P<0.001) was higher in PA than in PS individuals. Diversity for peanut allergens was greater in PA individuals (p<0.001). All IgE characteristics were correlated with basophil and mast cell activation. Peanut SA (R=0.447) and PD (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 was statistically different in PA and PS individuals. IgE Peanut SA and PD had the greatest influence on effector cell activation and could be employed clinically.
Oral immunotherapy for peanut allergy: The con argument
Background: In some countries of the world, peanut allergy represents an important source of anaphylactic reactions. Traditionally treated with the avoidance of responsible allergens, this condition can also be targeted by oral peanut immunotherapy.
Methods: In this study, we review the beneficial and side effects of currently available forms of peanut oral immunotherapy (POIT). We report the discussions resulting from the publication of a meta-analysis that brought to light the downsides of oral immunotherapy for peanuts.
Results: In some clinical situations, the risk-benefit ratio can favor peanut oral immunotherapy over avoidance. In many other situations, this is not the case. The decision must be based on the values and preferences of clinicians and patients. Those not ready to accept serious adverse effects from POIT are likely to continue the elimination diet; those motivated to achieving desensitization, and prepared to accept serious adverse effects, may choose to undergo POIT.
Conclusions: Without being prejudiced against peanut oral immunotherapy, we indicate the possible evolution of treatment for this condition is in a rapidly evolving broader scenario. Among the future options, sublingual immunotherapy, parenteral immunotherapy with modified allergens, transcutaneous immunotherapy, and the use of biologics will become important options.
Effect of roasted peanut allergen Ara h 3 protein on the sensitization of Caco-2 cells
Background: Roasted peanut is widely loved as a kind of food with rich taste. However, peanut allergy is one of the major threats to human health, which affects about 5% of children and 1.4-2% of adults in the world.
Results: To evaluate the sensitization mechanism of peanut allergen Ara h 3, Caco-2 cells as the model, which has the similar structure and function to differentiated small intestinal epithelial cells. Compared with Ara h 3-raw (purified from raw peanut) group, more significant results such as the inhibited Caco-2 cell viability and proliferation, the increased secretion of ROS and the decreased transepithelial electrical resistance were obtained in Ara h 3-roasted (purified from roasted peanut) group. Accordingly, oxidative stress and NF-κB signaling pathway were more imbalanced, which lead to the increased of TSLP, IL-6, IL-8 and MCP-1. Then the gene expression of tight junction proteins ZO-1, occludin and JAM-1 were down more, which proved the integrity of Caco-2 monolayer barrier is severely damaged.
Conclusion: These finding identify the mechanisms of the allergenicity of roasted peanut allergy proteins are probably associated with intestinal uptake and cytokinedependent allergies. The aggravated allergic reaction might be caused by the increment of TSLP, IL-6, IL-8 and MCP-1 due to the activated NF-κB signaling pathway, and the enhanced transport of Ara h 3-roasted protein by Caco-2 monolayer.
Food Allergy History and Reaction to Propofol Administration in a Large Pediatric Population
Background: Anaphylaxis to propofol is rare, however providers face a clinical quandary as medication warnings still exist regarding propofol administration to egg-, soy-, and peanut-allergic patients.
Aims: The primary aim evaluated the rate of allergic reactions during propofol-containing anesthesia in patients listed allergic to egg, soy, or peanut compared to non-allergic patients who received propofol. The secondary aim evaluated the relationship between food allergy history and allergy testing data.
Methods: A retrospective chart review conducted between May 2012 and October 2018 identified pediatric patients listed allergic to egg, soy, and/or peanut, who received propofol. Allergy testing and results are presented. Evidence of allergic reaction to propofol during anesthesia was evaluated, and compared to a large non allergic cohort who received propofol.
Results: Of the 232,392 anesthetics administered, 177,360 (76%) included propofol and 11308 (6%) involved a patient listed allergic to at least 1 index food. A large number of patients had no food allergy testing (n = 6153), or negative testing (n = 2198). Of the 3435 patients listed egg-allergic, 976 tested positive; 750, negative; and 1709, had no testing. Of the 2011 patients listed soy-allergic, 322 tested positive; 585, negative; and 1104, had no testing. Additionally, 5862 patients were listed peanut-allergic; 1659, tested positive; 863, tested negative and, 3340 had no testing. One record of proven propofol anaphylaxis occurred; it was in a patient without a history of food allergies. There were 6 other cases of suspected allergy to propofol. One had a peanut and tree nut allergy and was lost to follow up; one had no testing available, while 4 patients had positive propofol allergy testing and positive allergy tests to other medications. The rate of proven propofol anaphylaxis during anesthesia in the non-allergic cohort was 0.06/10,000, the rate in egg and soy allergic patients was 0/5,446. One patient with a listed peanut allergy had a possible reaction to propofol.
Conclusions: In the listed food-allergic cohort, the majority had no allergy testing or negative testing. We found no evidence of a relationship between food allergy history and perioperative propofol reaction. We suggest multiply allergic and atopic patients may have a similar likelihood of propofol reaction as with other medications.