Almond allergens: update and perspective on identification and characterization.

Almond is one of the tree nuts listed by U.S. FDA as a food allergen source. A food allergen identified with patient sera has been debated to be the 2S albumin or the 7S vicilin. However, neither of these proteins has been defined as a food allergen. The purpose of this study was to clone, express, and purify almond vicilin and test whether it is a food allergen. Western blot experiment was performed with 18 individual sera from patients with double-blind, placebo-controlled clinical almond allergy. The results showed that 44% of the sera contained IgE antibodies that recognized the recombinant almond vicilin, indicating that it is an almond allergen. Identifying this and additional almond allergens will facilitate the understanding of the allergenicity of seed proteins in tree nuts and their cross-reactivity.

Possession of epinephrine auto-injectors by Canadians with food allergies

Background: IgE-reactive proteins have been identified in almond; however, few have been cloned and tested for specific patient IgE reactivity. Here, we clone and express prunin 1 and prunin 2, isoforms of the major almond protein prunin, an 11S globulin, and assay each for IgE reactivity. Methods: Prunin isoforms were PCR-amplified from an almond cDNA library, sequenced, cloned and expressed in Escherichia coli. Reactivity to the recombinant (r) allergens, Pru du 6.01 and Pru du 6.02, was screened by dot blot and immunoblot assays using sera from almond-allergic patients and murine monoclonal antibodies (mAbs). Sequential IgE-binding epitopes were identified by solid-phase overlapping peptide analysis. Epitope stability was assessed by assaying denatured recombinant proteins by immunoblot. Results: IgE reactivity to rPru du 6.01 and rPru du 6.02 was found in 9 of 18 (50%) and 5 of 18 patients (28%), respectively. Four patients (22%) demonstrated reactivity to both isoforms. Murine anti-almond IgG mAbs also showed greater reactivity to rPru du 6.01 than to rPru du 6.02. Both stable and labile epitopes were detected. Six IgE-binding sequential epitope-bearing peptide segments on Pru du 6.01 and 8 on Pru du 6.02 were detected using pooled almond-allergic sera. Conclusions: rPru du 6.01 is more widely recognized than rPru du 6.02 in our patient population. The identification of multiple sequential epitopes and the observation that treatment with denaturing agents had little effect on IgE-binding intensity in some patients suggests an important role for sequential epitopes on prunins.

Differences In Food Allergy Quality Of Life Between Caregivers In a Clinic-Based and a Caregiver-Reported Food Allergic Population

The 2021 AAAAI Foundation Faculty Development awardees

Self-reported allergic reactions to peanut and tree nuts occurring on commercial airlines

Background: Incidents of severe and fatal anaphylaxis to accidentally ingested food allergens are increasing. Individuals are more likely to encounter difficulties when eating away from home. In restaurants, front-of-house and kitchen staff may be called upon to provide information about ingredients or ensure certain food allergens are excluded from dishes. Following a series of reactions related to the accidental ingestion of peanuts in curries we assessed food allergy awareness and allergen avoidance practices amongst the staff of Asian-Indian restaurants. Methods: A questionnaire survey was administered by telephone to one member of staff in each restaurant. Results: Fifty percent (40/80) of restaurants participated. Responders included managers, owners, waiters and chefs. Most (90%) had received food hygiene training, but only 15% food allergy training. 25% could name three common food allergens. 3 in 4 listed nuts, but less than 1in 5 mentioned peanuts. Common misunderstandings included 60% of staff believing an individual experiencing an allergic reaction should drink water to dilute the allergen. A less prevalent, but perhaps more concerning, was the misunderstanding that cooking food would prevent it causing an allergic reaction (25%). Despite poor knowledge, all respondents were comfortable and 65% were “very comfortable” with providing a “safe” meal for a customer with a food allergy. 60% expressed interest in future food allergy training. Conclusions: Despite high confidence in their own understanding of allergy, many staff lacked the knowledge to provide “safe” meals for food allergic customers. Traditionally tree nuts are a common ingredient in Asian-Indian dishes cuisine and there was widespread, but not universal, awareness of tree nuts as a common allergen. Peanuts were less commonly recognised as a common allergen, an observation of extreme concern as peanuts are being substituted for tree nuts as they are cheaper and avoid having to inflate meal prices. Our data highlights the need for greater training of restaurant staff. In parallel, food allergic customers need to exercise vigilance when making meal choices and develop skills to order a safe meal. The management of allergy is multifaceted, and this study indicates the importance of health professionals working beyond the clinical setting to collaborate with colleagues in the hospitality industry, public health and environmental health in coordinated endeavours to improve patient safety.

Background: Studies suggest an increase in food allergy prevalence over the last decade, but the contributing factors remain unknown. The aim of this study was to evaluate the association between the most common food allergies and atopic history, sociodemographic characteristics and lifestyle habits. Methods: We conducted a case-control study nested within the SPAACE study (Surveying Prevalence of Food Allergy in All Canadian Environments) - a cross-Canada, random telephone survey. Cases consisted of individuals with probable food allergy (self-report of convincing symptoms and/or physician diagnosis) to milk, egg, peanut, tree nut, shellfish, fish, wheat, soy, or sesame. Controls consisted of nonallergic individuals, matched for age. Cases and controls were queried on personal and family history of atopy, sociodemographic characteristics and lifestyle habits. Multivariate logistic regression was used to evaluate the association between atopy, sociodemographic characteristics and lifestyle habits with probable food allergy. Results: Between September 2010 and September 2011, 480 cases and 4,950 controls completed the questionnaire. For all 9 allergens, factors associated with a higher risk of probable allergy were as follows: (1) personal history of eczema (in the first 2 years of life), asthma or hay fever (odds ratio, OR 2.3, 95% CI 1.6-3.5; OR 2.8, 95% CI 2.2-3.6, and OR 2.3, 95% CI 1.8-3.0, respectively), (2) maternal, paternal or sibling's food allergy (OR 3.7, 95% CI 2.5-5.6; OR 3.0, 95% CI 1.8-5.1, and OR 3.1, 95% CI 2.2-4.2), (3) high household income (top 20%; OR 1.5, 95% CI 1.2-2.0). Males and older individuals were less likely to have food allergy (OR 0.7, 95% CI 0.6-0.9, and OR 0.99, 95% CI 0.99-1.00). Eczema in the first 2 years of life was the strongest risk factor for egg, peanut, tree nut and fish allergy. Conclusions: This is the largest population-based nested case-control study exploring factors associated with food allergies. Our results reveal that, in addition to previously reported factors, eczema in the first 2 years of life is consistently associated with food allergies.

A protocol for a systematic review to identify allergenic tree nuts and the molecules responsible for their allergenic properties

Epitopes with similar physicochemical properties contribute to cross reactivity between peanut and tree nuts

Food allergy is a costly, potentially life-threatening condition. Although studies have examined the prevalence of childhood food allergy, little is known about prevalence, severity, or health care utilization related to food allergies among US adults. To provide nationally representative estimates of the distribution, severity, and factors associated with adult food allergies. In this cross-sectional survey study of US adults, surveys were administered via the internet and telephone from October 9, 2015, to September 18, 2016. Participants were first recruited from NORC at the University of Chicago's probability-based AmeriSpeak panel, and additional participants were recruited from the non-probability-based Survey Sampling International (SSI) panel. Demographic and allergic participant characteristics. Self-reported food allergies were the main outcome and were considered convincing if reported symptoms to specific allergens were consistent with IgE-mediated reactions. Diagnosis history to specific allergens and food allergy-related health care use were also primary outcomes. Estimates were based on this nationally representative sample using small-area estimation and iterative proportional fitting methods. To increase precision, AmeriSpeak data were augmented by calibration-weighted, non-probability-based responses from SSI. Surveys were completed by 40 443 adults (mean [SD] age, 46.6 [20.2] years), with a survey completion rate of 51.2% observed among AmeriSpeak panelists (n = 7210) and 5.5% among SSI panelists (n = 33 233). Estimated convincing food allergy prevalence among US adults was 10.8% (95% CI, 10.4%-11.1%), although 19.0% (95% CI, 18.5%-19.5%) of adults self-reported a food allergy. The most common allergies were shellfish (2.9%; 95% CI, 2.7%-3.1%), milk (1.9%; 95% CI, 1.8%-2.1%), peanut (1.8%; 95% CI, 1.7%-1.9%), tree nut (1.2%; 95% CI, 1.1%-1.3%), and fin fish (0.9%; 95% CI, 0.8%-1.0%). Among food-allergic adults, 51.1% (95% CI, 49.3%-52.9%) experienced a severe food allergy reaction, 45.3% (95% CI, 43.6%-47.1%) were allergic to multiple foods, and 48.0% (95% CI, 46.2%-49.7%) developed food allergies as an adult. Regarding health care utilization, 24.0% (95% CI, 22.6%-25.4%) reported a current epinephrine prescription, and 38.3% (95% CI, 36.7%-40.0%) reported at least 1 food allergy-related lifetime emergency department visit. These data suggest that at least 10.8% (>26 million) of US adults are food allergic, whereas nearly 19% of adults believe that they have a food allergy. Consequently, these findings suggest that it is crucial that adults with suspected food allergy receive appropriate confirmatory testing and counseling to ensure food is not unnecessarily avoided and quality of life is not unduly impaired.

Background: Food allergies (FA) are an important public health concern that place a major burden on the lives of children and their families. The complex pathogenesis of FAs results in multisystemic and heterogenous clinical presentations. Objective: To evaluate, according to immune mechanisms, the characteristics and risk factors of childhood FA in Turkey. Methods: This descriptive multicenter study included 1248 children with FA, aged < 18 years,, who were evaluated by pediatric allergists in 26 different centers. Results: Immune mechanisms of FA were immunoglobulin E (IgE) mediated in 71.8%, non-IgE mediated in 15.5%, and mixed IgE/non-IgE mediated in 12.7% of the patients. An episode of anaphylaxis had occurred in 17.6% of IgE-mediated FA. The most common food allergens were classified into five categories (in order of decreasing frequency): cow's milk, egg, tree nuts and/or peanut, wheat, and seafood. Allergies to cow's milk and egg declined significantly with age, whereas tree nuts and/or peanut allergies increased with age. The 0-2 year age group accounted for 62.5% of the cases. The most frequent cause of FA and food anaphylaxis was cow's milk before age 13 years and tree nuts and/or peanut during adolescence (ages 13-18 years). Compared with other phenotypes, male sex (odds ratio [OR] 1.486; p = 0.032), sibling(s) (OR 1.581; p = 0.021), and maternal atopy (OR 1.531; p = 0.045) increased the likelihood of IgE-mediated FA, whereas high household income (OR 1.862; p = 0.026) increased the likelihood of non-IgE-mediated FA in multivariate regression analysis. Conclusion: This study showed that the clinical findings of FA were highly variable, depending on age and underlying immune mechanism. Knowing the population characteristics will enable better management of FA in children.

Food allergies appear to be one of the foremost causes of hypersensitivity reactions. Nut allergies account for most food allergies and are often permanent. The 360 kDa hexameric protein Pru du amandin, a known allergen, was purified from almonds (Prunus dulcis) by ammonium sulfate fractionation and ion-exchange chromatography. The protein was identified by a BLAST homology search against the nonredundant sequence database. Pru du amandin belongs to the 11S legumin family of seed storage proteins characterized by the presence of a cupin motif. Crystals were obtained by the hanging-drop vapour-diffusion method. The crystals belong to space group P4(1) (or P4(3)), with unit-cell parameters a = b = 150.7, c = 164.9 A.

Prevalence of Physician-Reported Food Allergy in Canadian Children

There are a number of examples of immunologic cross-reactivity elicited by pollens, fruits, seeds, and nuts of closely related plant species. Such cross-reactivity is of particular concern for patients with food allergies. In this report, we investigated a spice (mahleb) that is prepared from the kernel of the St. Lucie cherry, Prunus mahaleb, for cross-reactivity with almond (Prunus dulcis), using enzyme-linked immunosorbent assay (ELISA) and Western blot. Almond and mahleb are members of the same genus. Cross-reactivity between the mahleb and almond was demonstrated by reaction of cherry and almond kernel protein extracts with antibodies raised against almond proteins. Almond-specific murine monoclonal IgG, rabbit polyclonal IgG, and almond-allergic serum IgE each exhibited cross-reactivity with cherry kernel protein. Because of the demonstrated cross-reactivity between almond and mahleb, these findings should be of special concern to almond-allergic patients and attending medical personnel.