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.
Phenotypical characterization of peanut allergic children with differences in cross‐allergy to tree nuts and other legumes.
BACKGROUND: Peanut allergy in children is often associated with allergies to tree nuts and/or legumes. The aim of the present study was to analyze in cluster a cohort of children allergic to peanuts and assessed for cross-reactivity to nuts and legumes and to identify different phenotypes. METHODS: We included retrospectively 317 children with peanut allergy evaluated at the Allergy Unit of the Saint Vincent Hospital of Lille in the last 12 years. A complete work-up for peanut allergy and nuts and legumes was carried out for each patient. A hierarchical agglomerative clustering method was used to search for clusters of individuals in the evaluated cohort. RESULTS: Cross-allergy to TN and/or other legumes was identified in 137 patients (43.2%), atopic dermatitis being a major risk factor (adjusted OR = 16 [95%CI: 7.4-37]; p<0.001). Three phenotypes emerged from cluster analysis. Cluster 1 (72 patients) is characterized by high level of rAra h 2, low threshold reactive doses for peanut and high proportion of asthma; Cluster 2 (93 patients) is characterized by high threshold reactive doses for peanut and the lowest proportion of cross-allergy to TN and/or legumes; Cluster 3 (152 patients) has a high risk of cross-allergy to TN and/or legumes and most patients suffer from eczema. CONCLUSIONS: The three phenotypes highlighted by the present study could be useful to identify children with high risk of cross-allergic reaction to TNs and legumes early after PA diagnosis.
Can pan-allergens affect the sensitization pattern?
The present study tested the hypothesis that a pan-allergen sensitization may affect the sensitization pattern. For this reason, 22 sensitization pattern allergens (SPA), common in Genoa (Italy), were selected for analyses. Successively, five of them, such as Pru p 3 as representative for LTP family, Bet v 1 and Pru p 1 for PR-10, and Bet v 2 and Pru p 4 for Profilin, were used as target allergens (TA). This retrospective study included 1059 subjects, (396 males and 663 females, mean age 42.8 years). The current study showed that sensitization to a pan-allergen entails higher odds to have other sensitizations. In addition, the co-sensitization pattern depends on the basis of the sensitizing pan-allergen family. LTP-sensitization is strongly associated with peanut sensitization, PR10 and profiling sensitization with hazelnut positivity. This study shows that a pan-allergen sensitization is frequently associated with co-sensitizations and the sensitization pattern depends on the sensitizing pan-allergen.
Review suggests that the immunoregulatory and anti‐inflammatory properties of allergenic foods can provoke oral tolerance if introduced early to infants’ diets.
For years, the advice was to postpone introducing allergenic foods, in order to prevent food allergies. However, food allergies have escalated rather than declined and our review of the latest epidemiological, immunological and nutritional research suggests that early weaning practices may be beneficial. The most allergenic foods, such as fish, eggs and peanuts, have proved to be inherently rich in tolerogenic substances that can play a significant role in preventing allergies. CONCLUSION: We found evidence that the immunoregulatory and anti-inflammatory properties of allergenic foods can provoke oral tolerance if introduced early to both low-risk and high-risk infants.