Early introduction of peanuts.
Peanut allergy is the most common food allergy and the leading cause of anaphylaxis and death due to food allergy. Despite previous guidelines created by the American Academy of Pediatrics in 2003, peanut allergy has continued to significantly increase over the past decade. Therefore, further research has been done to help clinicians provide more evidence-based recommendations about the timing of introduction of peanuts. The LEAP study, published in February 2015, demonstrated the value of much earlier introduction of peanuts to nonallergic patients than previously suggested. These findings have altered current practice, and recommendations supported by the American Academy of Pediatrics now allow the introduction of peanuts as early as age 4 months to reduce the likelihood of developing peanut allergy.
A Novel Immunoassay Test System for Detection of Modified Allergen Residues Present in Almond-, Cashew-, Coconut-, Hazelnut-, and Soy-Based Nondairy Beverages.
A growing number of plant-based milk substitutes have become commercially available, providing an array of options for consumers with dietary restrictions. Though several of these products rival cow's milk in terms of their nutritional profiles, beverages prepared with soy and tree nuts can be a significant concern to consumers because of potential contamination with food allergens. Adding to this concern is the fact that allergen residues from plant-based beverages are modified during manufacturing, thereby decreasing the sensitivity of antibody-based detection methods. Consequently, many commercially available allergen detection kits are less effective for allergens derived from nondairy milk substitutes. To address this limitation, we developed a panel of polyclonal antibodies directed against the modified proteins present in almond, cashew, coconut, hazelnut, and soy milks and incorporated them into rapid lateral flow immunoassay tests configured in both sandwich and competitive format. The tests had robust detection capabilities when used with a panel of various brand-name products, with a sensitivity of 1 ppm and selectivity values of 3 to 5 ppm in nondairy beverages. Minimal cross-reactivity to extracts prepared from common commodities was observed. The development of a highly sensitive and rapid test specifically designed to detect trace quantities of highly modified allergen residues in plant-based, dairy-free beverages will aid food manufacturers and regulatory agencies in monitoring products for these modified allergens when testing environmental and food samples.
Validation of Recipes for Double-Blind Placebo-Controlled Challenges With Milk, Egg White, and Hazelnut.
BACKGROUND: The double-blind, placebo-controlled food challenge (DBPCFC) is considered the definitive diagnostic test for food allergy. Nevertheless, validated recipes for masking the foods are scarce, have not been standardized, and differ between centers. Sensory evaluation techniques such as the triangle test are necessary to validate the recipes used for DBPCFC. METHODS: We developed 3 recipes for use in DBPCFC with milk, egg white, and hazelnut and used the triangle test to validate them in a 2-phase study in which 197 volunteers participated. In each phase, participants tried 3 samples (2 active-1 placebo or 2 placebo-1 active) and had to identify the odd one. In phase 1, the 3 samples were given simultaneously, whereas in phase 2, the 3 samples of foods that failed validation in phase 1 were given sequentially. A visual analog scale (VAS) ranging from 1 to 10 was used to evaluate how much participants liked the recipes. RESULTS: In phase 1, the egg white recipe was validated (n=89 volunteers, 38.9% found the odd sample, P=.16). Milk and hazelnut recipes were validated in phase 2 (for both foods, n=30 participants, 36.7% found the odd sample, P=.36). Median VAS scores for the 3 recipes ranged from 6.6 to 9.7. CONCLUSIONS: We used sensory testing to validate milk, egg white, and hazelnut recipes for use in DBPCFC. The validated recipes are easy to prepare in a clinical setting, provide the equivalent of 1 serving dose, and were liked by most participants.
A Multi‐Center Study on Anaphylaxis caused by Peanut, Tree Nuts and Seeds in Children and Adolescents.
Peanut (PN) and tree nuts (TNs) are common causes of anaphylaxis in Western countries, but no information is available in Korea. To feature clinical characteristics of anaphylaxis caused by PN, TNs, and seeds, a retrospective medical record review was performed in 14 university hospitals in Korea (2009-2013). One hundred and twenty-six cases were identified, with the mean age of 4.9 years. PN, walnut (WN), and pine nut accounted for 32.5%, 41.3%, and 7.1%, respectively. The median values of specific IgE (sIgE) to PN, WN, and pine nut were 10.50, 8.74, and 4.61 kUA /l, respectively. Among 50 cases managed in the emergency department, 52.0% were treated with epinephrine, 66.0% with steroid, 94.0% with antihistamines, 36.0% with oxygen, and 48.0% with bronchodilator. In conclusion, WN, PN, and pine nut were the three most common triggers of anaphylaxis in Korean children, and anaphylaxis could occur at remarkably low levels of sIgE.
Identifying Epithelial Endocytotic Mechanisms of the Peanut Allergens Ara h 1 and Ara h 2.
BACKGROUND: Peanuts are still one of the highest contributors to anaphylactic deaths after ingestion of a food allergen. At the molecular level, interactions between peanut allergens and the intestinal epithelium are largely unexplored. Previous findings by our research group demonstrated that the major peanut allergens, i.e., Ara h 1, Ara h 2, Ara h 3, and Ara h 6, were able to cross the Caco-2 human cell culture model of the intestinal epithelium. This research broadened our investigation to identify the mechanisms by which the Caco-2 monolayers uptake peanut allergens, specifically by endocytosis. Here, we aim to increase our understanding of allergen-epithelial interactions and, more broadly, the pathway from allergen to allergy. METHODS: The human Caco-2 cell culture model was exposed to peanut extract and a combination of confocal microscopy and inhibition studies were used to identify the endocytotic mechanisms of peanut allergens in intestinal epithelia. RESULTS: Our findings demonstrate that the peanut allergens Ara h 1 and Ara h 2 are transported through intestinal epithelia initially via early endosomes using multiple endocytotic mechanisms. From there, they are then transported to late endosomes and ultimately to lysosomes. CONCLUSIONS: These novel findings provide insight into the allergen-epithelial interactions of peanut allergens with the intestinal epithelium. Consequently, this opens the possibility of the use of these endocytotic pathways as targets for inhibitors in therapeutic development and preventative measures for peanut allergy in the future.
Low percentage of clinically relevant pistachio nut and mango co-sensitisation in cashew nut sensitised children.
BACKGROUND: Cashew nut, pistachio nut and mango belong to the Anacardiaceae family and are botanically related. Therefore, cashew nut sensitised children are frequently advised to eliminate cashew nuts and pistachio nuts from their diet. The 'Improvement of Diagnostic mEthods for ALlergy assessment (IDEAL trial number NTR3572) study showed that cashew nut sensitised children were co-sensitised to pistachio nut in 98% of cases and to mango in 21% of cases. The aim of this follow-up study to IDEAL is to assess the clinical relevance of co-sensitisation to pistachio nut and mango in cashew nut sensitised children. METHODS: Children were recruited from the study: 'Improvement of Diagnostic mEthods for ALlergy assessment (IDEAL trial number NTR3572). Inclusion criterion for the IDEAL study was sensitization to cashew nut as demonstrated by either SPT or sIgE, and a clinical history of reactions to cashew nuts or no previous (known) exposure. Sensitized children who were tolerant to cashew nuts were excluded. Inclusion criterion for this IDEAL follow-up study was co-sensitization to pistachio nut, regardless the result of the DBPCFC with cashew nut. In this follow-up study a double-blind placebo-controlled food challenge with pistachio nut and an open food challenge with mango were performed. RESULTS: Twenty-nine children (mean age of 11.6 years, 62% male) were included. Pistachio nut sensitisation was clinically relevant in only 34% of cashew-sensitised children and only 31% of cashew challenge positive children. None of the children was challenge positive to mango. CONCLUSION: Although co-sensitisation between cashew nut and pistachio nut was observed in 98%, pistachio nut sensitisation was only clinically relevant in 34% of the children. Therefore, a challenge test with pistachio nut is recommended in children with cashew nut and pistachio nut sensitisation. Trial registration The study was registered in the Dutch trial register (registration number 3572) on 10 August 2012 (retrospectively registered).
Detection of Food Allergens by Taqman Real-Time PCR Methodology.
Real-time PCR (polymerase chain reaction) has shown to be a very effective technology for the detection of food allergens. The protocol described herein consists on a real-time PCR assay targeting the plant ITS (Internal Transcribed Spacer) region, using species-specific primers and hydrolysis probes (Taqman) dual labeled with a reporter fluorophore at the 5' end (6-carboxyfluorescein, FAM) and a quencher fluorophore at the 3' end (Blackberry, BBQ). The species-specific real-time PCR systems (primers/probe) described in this work allowed the detection of different nuts (peanut, hazelnut, pistachio, almond, cashew, macadamia, walnut and pecan), common allergens present in commercial food products, with a detection limit of 0.1 mg/kg.
Detection of Food Allergens by Phage-Displayed Produced Antibodies.
Phage display is a powerful tool to produce recombinant antibodies against a given antigen without animal immunization. This technology employs libraries of recombinant bacteriophages that display billions of different functional antibody fragments on their surface. They are selected by panning in vitro against the target antigen in search for specific binders. In this chapter, we describe the selection of single chain variable fragment (scFv) antibodies to be used for detection of allergenic proteins from nuts in food products. The artificial libraries TomLinson I+J (MRC Laboratory of Molecular Biology and MRC Centre for Protein Engineering) were employed that resulted in successful phage-ELISA systems for detection of almond and walnut proteins in commercial food products.
A Limited Survey of Dark Chocolate Bars Obtained in the United States for Undeclared Milk and Peanut Allergens.
Undeclared allergens in chocolate products have been responsible for numerous allergen-related recalls in the United States. A survey was conducted to determine the prevalence of undeclared milk and peanut in 88 and 78 dark chocolate bars, respectively. Concentrations of milk (as nonfat dry milk) or peanut in three samples of each chocolate product were determined with two milk- or peanut-specific enzyme-linked immunosorbent assay kits. In 75% of the chocolate bar products with a milk advisory statement, milk concentrations were above the limit of quantitation (2.5 μg/g [ppm]), with the majority having concentrations >1,000 ppm. An additional 67% of chocolate bars with a "traces of milk" statement contained 3 to 6,700 ppm of milk. Fifteen percent of chocolates labeled dairy free or lactose free and 25% labeled vegan were positive for milk, all with concentrations >1,000 ppm. Even for chocolates with no reference to milk on the label, 33% of these products contained 60 to 3,400 ppm of milk. The survey of chocolate products for peanuts revealed that 8% of products with an advisory statement contained peanut, with the highest concentration of 550 ppm. All nine chocolates bearing the peanut-free or allergen-free statement were negative for peanut, but 17% of chocolates with no label statement for peanut were positive for peanut at concentrations of 9 to 170 ppm. Evaluation of multiple lots of four chocolate products revealed that milk was consistently present or absent for the products investigated, but mixed results were obtained when multiple lots were tested for peanut. This study indicates that a large proportion of dark chocolate bars contain undeclared milk. The type of advisory statement or the absence of a milk advisory statement on products did not predict the amount or absence of milk protein. In contrast, a lower proportion of chocolates containing undeclared peanut was found. Consumers with food allergies should be cautious when purchasing dark chocolate products, particularly those that have an advisory label statement.
Peanut Allergen Threshold Study (PATS): Novel single-dose oral food challenge study to validate eliciting doses in peanut allergic children.
BACKGROUND: Eliciting doses (ED) of allergenic foods can be defined by the distribution of threshold doses for individuals within a specific population. ED05 is the dose that elicits a reaction in 5% of allergic subjects. The predicted ED05 for peanut (PN) is 1.5 mg of peanut protein (6 mg whole peanut). OBJECTIVE: We sought to validate the predicted peanut ED05 (1.5 mg) with a novel single dose challenge. METHODS: Consecutive eligible peanut allergic children in 3 centres were prospectively invited to participate, irrespective of previous reaction severity. Predetermined criteria for objective reactions were used to identify ED05 single dose reactors. RESULTS: 518 children (mean age 6.8 years) were eligible. No significant demographic or clinical differences were identified between 381(74%) participants and 137 (26%) non-participants or between subjects recruited at each centre. 378 children (206 male) completed the study. Almost half the group reported ignoring precautionary allergen labelling. 245 (65%) experienced no reaction to the single dose of peanut. 67 (18%) reported a subjective reaction without objective findings. 58 (15%) experienced signs of a mild and transient nature that did not meet the pre-determined criteria. Only 8 subjects (2.1%, 95% CI 0.6%-3.4%) met the pre-determined criteria for an objective and likely related event. No child experienced more than a mild reaction, 4 of the 8 received oral antihistamines only and none received epinephrine. Food allergy related quality of life improved from baseline to 1 month post challenge regardless of outcome (eta squared = 0.2, p <0.0001). Peanut SPT, peanut and Ara h 2 spIgE levels were not associated with objective reactivity to PN ED05. CONCLUSION: A single administration of 1.5 mg PN protein elicited objective reactions in fewer than the predicted 5% of peanut-allergic subjects. The novel single dose OFC appears clinically safe and patient-acceptable, regardless of the outcome. It identifies the most highly dose-sensitive food allergic population, not otherwise identifiable using routinely available peanut SPT or spIgE levels but this single-dose approach has not yet been validated for risk assessment of individual patients.