Almond Allergy: An Overview on Prevalence, Thresholds, Regulations and Allergen Detection.
Food allergy has been on the increase for many years. The prevalence of allergy to different foods varies widely depending on type of food, frequency of consumption and geographic location. Data from the literature suggests that the prevalence of tree nut allergy is of the order of 1% in the general population. Almond is one such tree nut that is frequently eaten in many parts of the world and represents a potential allergenic hazard. Given the need to label products that contain allergens, a number of different methods of direct and indirect detection have been developed. However, in the absence of population-based threshold data, and given that almond allergy is rare, the sensitivity of the required detection is unknown and thus aims as low as possible. Typically, this is less than 1 ppm, which matches the thresholds that have been shown for other allergens. This review highlights the lack of quantitative data on prevalence and thresholds for almonds, which is limiting progress in consumer protection.
Correlation of negative skin-prick test results for tree nuts and successful tree nut challenges among children with peanut allergy.
Background: Children with peanut allergy are regularly instructed to avoid all tree nuts. However, children with peanut allergy are likely not allergic to all tree nuts. Objective: In our cohort of patients with peanut anaphylaxis and who underwent oral immunotherapy, we sought to determine the correlation of skin-prick testing (SPT) results for tree nuts and the likelihood of successfully passing a tree nut challenge. Methods: SPT was performed for peanut and tree nuts (macadamia, pine nut, coconut, hazelnut, brazil nut, cashew, pecan, walnut, pistachio, almond) in 27 patients with known peanut allergy. The probability of a negative SPT result (wheal < 3 mm) for each nut was determined. Results: All the patients demonstrated positive results in peanut allergy diagnostics in SPT, component testing, or food challenge. Only 15.4% of the patients had a positive SPT result to peanut alone. Macadamia, pine nut, and coconut SPT had a probability of negative SPT results of 0.97, 0.97, and 0.91, respectively. The odds ratio for this group having a negative SPT was 46.22. For hazelnut, Brazil nut, and cashew, the probability of a negative SPT result was 0.81, 0.77, and 0.73, respectively. Pecan, walnut, and pistachio had odds ratios of 0.68, 0.68, and 0.64, respectively. All the patients with macadamia, pine nut, and coconut negative SPT results subsequently passed 9-g food challenges without oral immunotherapy. Conclusion: Despite current recommendations to avoid all tree nuts for patients with peanut allergy, the majority of patients with peanut allergy had negative SPTs and food challenges to certain tree nuts, especially macadamia, pine nut, and coconut. This pattern was seen despite most patients having multiple nut sensitizations.
Comparing the eating out experiences of consumers seeking to avoid different food allergens.
BACKGROUND: Eating outside the home is challenging for consumers with food allergy (FA) and intolerance (FI) and lack of allergen information provision in eating out venues can lead to unnecessary restrictions. Following European legislation (2014) designed to improve allergen information provision, little is known about differences in information provision experienced by consumers seeking to avoid particular allergens, or how this impacts on their eating out experiences. This study compared the information provision that consumers with FA/FI to different allergens experience when eating out. METHODS: Using mixed methods, participants were recruited from across the UK and took part in self-report surveys or in-depth interviews. Surveys were completed by 232 participants avoiding either gluten (n = 66), nuts (peanuts/tree nuts) (n = 94), or milk (n = 74), and responses were subject to quantitative analyses. Interviews were carried out with 49 participants avoiding either gluten (n = 13), nuts (n = 14), milk (n = 13) or a combination of these allergens (n = 9), and analysed using the framework approach. RESULTS: Although general improvements in information provision following the legislation were reported, variations in provision between allergen groups led participants seeking to avoid milk to conclude that their dietary needs were less well-understood and seen as less important. These perceptions were reflected in a reluctance to involve eating out venue staff in deliberations about the potential for milk-free meal options. CONCLUSIONS: The provision of visual indicators of the presence of milk and of staff trained in allergen-awareness would improve the eating out experiences of consumers seeking to avoid milk. Medical professions can play a key role in encouraging these patients to pursue their right to make enquiries about allergens in order to avoid accidental milk ingestion when eating out.
Adjuvanted Immunotherapy Approaches for Peanut Allergy.
Food allergies are a growing public health concern with an estimated 8% of US children affected. Peanut allergies are also on the rise and often do not spontaneously resolve, leaving individuals at-risk for potentially life-threatening anaphylaxis throughout their lifetime. Currently, two forms of peanut immunotherapy, oral immunotherapy (OIT) and epicutaneous immunotherapy (EPIT), are in Phase III clinical trials and have shown promise to induce desensitization in many subjects. However, there are several limitations with OIT and EPIT, such as allergic side effects, daily dosing requirements, and the infrequent outcome of long-term tolerance. Next-generation therapies for peanut allergy should aim to overcome these limitations, which may be achievable with adjuvanted immunotherapy. An adjuvant can be defined as anything that enhances, accelerates, or modifies an immune response to a particular antigen. Adjuvants may allow for lower doses of antigen to be given leading to decreased side effects; may only need to be administered every few weeks or months rather than daily exposures; and may induce a long-lasting protective effect. In this review article, we highlight examples of adjuvants and formulations that have shown pre-clinical efficacy in treating peanut allergy.
Genetic Diversity Between Mouse Strains Allows Identification of CC027/GeniUnc as an Orally Reactive Model of Peanut Allergy.
BACKGROUND: Improved animal models are needed to understand the genetic and environmental factors that contribute to food allergy. OBJECTIVE: Assess food allergy phenotypes in a genetically diverse collection of mice. METHODS: We selected 16 Collaborative Cross (CC) mouse strains, as well as the classic inbred C57BL/6J, C3H/HeJ, and BALB/cJ strains for screening. Female mice were sensitized to peanut intragastrically with or without Cholera toxin, then challenged with peanut by oral gavage or intraperitoneal injection, and assessed for anaphylaxis. Peanut-specific immunoglobulins, T cell cytokines, Tregs, mast cells, and basophils were quantified. RESULTS: Eleven of the 16 CC strains had allergic reactions to intraperitoneal peanut challenge, whereas only CC027/GeniUnc mice reproducibly experienced severe symptoms following oral food challenge (OFC). CC027/GeniUnc, C3H/HeJ, and C57BL/6J all mounted a Th2 response against peanut, leading to the production of IL-4 and IgE but only the CC027/GeniUnc mice reacted to OFC. Orally-induced anaphylaxis in CC027/GeniUnc mice was correlated with serum levels of Ara h 2 in circulation, but not with allergen-specific IgE or MMCP-1 levels, indicating systemic allergen absorption is important for anaphylaxis through the gastrointestinal tract. Furthermore, CC027/GeniUnc mice, but not C3H/HeJ or BALB/cJ, can be sensitized in the absence of Cholera toxin and react upon OFC to peanut. CONCLUSIONS:
We have identified and characterized CC027/GeniUnc mice as a strain that is genetically susceptible to peanut allergy and prone to severe reactions following OFC. More broadly, these findings demonstrate the untapped potential of the CC population in developing novel models for allergy research.
Oral peanut immunotherapy‐How much is too much? How much is enough?.
Efficacy of Food allergy immunotherapy (FA-AIT) for cow's milk, hen's egg and peanut at the level of desensitization is established via several small placebo-controlled trials and a number of open label trials1 . First approved treatments for peanut allergy are projected to become available soon including oral immunotherapy (OIT). But there is still a discussion which group of patients might profit most of OIT and what amount of maintenance dose to apply.
Ara h 1 and Ara h 6 Sensitization Causes Clinical Peanut Allergy in Ara h 2-Negative Individuals.
BACKGROUND: Of the major peanut allergens, sensitivity to Ara h 2 has the highest prediction for clinical allergy. In this study, we evaluated sensitization to peanut components in Iceland and related Ara h 2-negative sensitization to clinical allergy. METHODS: Ara h 1, Ara h 2, Ara h 3, Ara h 8, and Bet v 1 IgEs were measured (ImmunoCAP) in 220 peanut IgE (Pn-IgE)-positive serum samples. Ara h 2 IgE-negative individuals were invited to an open peanut challenge and evaluated for Ara h 6 and 9 sensitization (ISAC microarray). RESULTS: The Ara h 2 IgE-negative group (52.3%, 115/220) was older (p = 0.04) and more likely to have a history of pollen allergy than the Ara h 2-positive group (p < 0.001). Of the Ara h 2-negative participants, 24.3% were already consuming peanuts and 38.3% were unavailable. Of the 43 who underwent an open peanut challenge, 79% were negative, 14% were positive, and 7% were inconclusive. Those who reacted to peanuts had a higher Ara h 1 IgE than that of the tolerant participants, and 3 were positive to Ara h 6 IgE, and 2 of those subjects were monosensitized. Ara h 8 may have caused a positive reaction, while Ara h 9 did not. CONCLUSIONS: Half of the peanut-sensitized individuals in Iceland were not sensitized to the major allergen Ara h 2. Ara h 1, Ara h 3, and Ara h 6 sensitizations resulted in a positive open peanut challenge and they are therefore clinically important for individuals with a peanut allergy in Iceland.
Boiling and roasting treatment affecting the peanut allergenicity.
BACKGROUND: Peanut allergy appears to be less prevalent in other parts of the world than North America and several European countries, and it has been proposed difference in cooking practices may be responsible. In this study, the boiling and roasting processes were investigated to find a potential method to enhanced or reduce the allergenicity. METHODS: The allergenicity of different peanut products, as reflected by changes in ethology (diarrhea and weight loss) and pathology (splenomegaly and jejunum breakage) were observed, and relevant serological indexes were determined after feeding different peanut products. Different peanut proteins were used to analyze the ability to resistance digestion in simulated gastric fluid (SGF). Ultraviolet spectrum and CD spectra were used to analyze structure changes of Ara h 2 in roasting and boiling treatment. RESULTS: In the detection of the corresponding serological indicators, boiled peanuts show a lower sensitization than roasted and raw peanuts. SGF experiments demonstrated an increased resistance of roasted peanut protein to digestion. The results of ultraviolet spectrum and CD spectra showed that the roasting and boiling causes altered structures of the Ara h 2 peanut allergens. CONCLUSIONS: The summary show that different thermal processing may affect the structure and immunoreactivity, and the sensitization of roasted or boiled peanuts will be enhanced or reduced.
IgE Cross-Reactivity of Cashew Nut Allergens.
BACKGROUND: Allergic sensitisation towards cashew nut often happens without a clear history of eating cashew nut. IgE cross-reactivity between cashew and pistachio nut is well described; however, the ability of cashew nut-specific IgE to cross-react to common tree nut species and other Anacardiaceae, like mango, pink peppercorn, or sumac is largely unknown. OBJECTIVES: Cashew nut allergic individuals may cross-react to foods that are phylogenetically related to cashew. We aimed to determine IgE cross-sensitisation and cross-reactivity profiles in cashew nut-sensitised subjects, towards botanically related proteins of other Anacardiaceae family members and related tree nut species. METHOD: Sera from children with a suspected cashew nut allergy (n = 56) were assessed for IgE sensitisation to common tree nuts, mango, pink peppercorn, and sumac using dot blot technique. Allergen cross-reactivity patterns between Anacardiaceae species were subsequently examined by SDS-PAGE and immunoblot inhibition, and IgE-reactive allergens were identified by LC-MS/MS. RESULTS: From the 56 subjects analysed, 36 were positive on dot blot for cashew nut (63%). Of these, 50% were mono-sensitised to cashew nuts, 19% were co-sensitised to Anacardiaceae species, and 31% were co-sensitised to tree nuts. Subjects co-sensitised to Anacardiaceae species displayed a different allergen recognition pattern than subjects sensitised to common tree nuts. In pink peppercorn, putative albumin- and legumin-type seed storage proteins were found to cross-react with serum of cashew nut-sensitised subjects in vitro. In addition, a putative luminal binding protein was identified, which, among others, may be involved in cross-reactivity between several Anacardiaceae species. CONCLUSIONS: Results demonstrate the in vitro presence of IgE cross-sensitisation in children towards multiple Anacardiaceae species. In this study, putative novel allergens were identified in cashew, pistachio, and pink peppercorn, which may pose factors that underlie the observed cross-sensitivity to these species. The clinical relevance of this widespread cross-sensitisation is unknown.
Effects of thermal treatment on walnut detection and allergenicity.
BACKGROUND: Peanuts and tree nut allergies pose an increasing food safety problem. The aim of our study was to test the accuracy of different commercial ELISA kits in the detection of the presence of walnuts in untreated and heat exposed food samples. The evaluation of the effects of thermal treatment in samples was tested exposing walnuts to different heat treatments. All samples were firstly analyzed by two different commercial ELISA assays. Then, we performed Skin Prick test (SPT) on nine patients with proven nuts allergy using small walnut pieces from raw and treated samples. RESULTS: The presence of nuts proteins in thermally processed foods was not accurately detected by ELISA kits. All patients had a positive SPT reaction with raw walnut, while thermal treatments affected walnut allergenicity. ELISA test gives a negative result in case of strong thermal treatment, but at the same time allergic subjects react positive at the stimulation with the same sample. CONCLUSION: This study suggest that commercial ELISA kits may not be able to accurately determine the amount of proteins present in thermally processed foods due to changes in the solubility and immunoreactivity of the target proteins. Finally, the clinical results highlight that thermal treatment might induce a reduction in walnut allergenicity.