Allergic Individuals Research Articles

Peanut and hazelnut occurrence as allergens in foodstuffs with precautionary allergen labeling in Canada

Precautionary allergen labeling (PAL) is widely used by food industries. Occurrence studies revealed that few analyzed products contained the allergen(s) present in the statement, but little is known in Canada. To improve manufacturing practices and better manage allergen cross-contamination, occurrence data is needed to determine the exposure of allergic individuals eating those products. Samples were analyzed for peanuts (n = 871) and hazelnuts (n = 863) using ELISA methods. Within samples analyzed for peanuts, 72% had a PAL (n = 628), 1% had peanuts as a minor ingredient (n = 9) and 27% were claimed “peanut-free” (n = 234). Most hazelnut samples had a PAL for tree nuts/hazelnuts (94%; n = 807) with 6% claimed “nut-free” (n = 56). Peanuts and hazelnuts were found in 4% (0.6–28.1 ppm) and 9% (0.4–2167 ppm) of all samples, respectively. Chocolates were mostly impacted; they should be treated apart from other foods and used in risk assessments scenarios to improve manufacturing practices, reducing unnecessary PAL use.

Psychosocial impact of peanut allergy in France: Results of the APPEAL survey

Introduction Peanut allergy (PA) is common and often involved in the most severe anaphylactic reactions. The aim of this survey was to investigate the psychosocial impact of PA in France. Methodes The results from French participants to the pan-European study Allergy to Peanuts imPacting Emotions And Life (APPEAL) designed to assess the psychosocial impact of PA are reported here. Participants were adults affected by PA directly or indirectly (caregivers) and they completed an online questionnaire. Resultats A total of 198 responders (60 adults with PA, 138 caregivers). 88% stated that PA affects their daily activities, and 74% felt isolated as a result of living with PA. Feelings of worry about exposure to peanuts on social occasions where food is involved was reported by 91%. A total of 44% reported some restrictions in their job options, 85% in socializing. Psychological impact of PA included responders feeling emotions of frustration (89%), uncertainty (87%), and stress (93%). Of the 115 responders prescribed adrenaline auto-injectors, 62 (54%) had their device always or very frequently; 32 (28%) and 21 (18%) had the device rarely or never; 72 (63%) had never used one and most felt not at all confident (31%) or very little confident (27%) in knowing when and how to use one. Conclusion These results demonstrate the psychosocial impact of PA on allergic individuals and their caregivers in France, and highlight the need to include a psychological evaluation during personalized care and treatment of individuals with PA.

The importance of component-resolved diagnostics in IgE-mediated cow's milk allergy.

Cow's milk allergy (CMA) is an increasingly common problem among children and adults that requires the use of appropriate diagnostics to eliminate allergic reactions and prevent unnecessary dietary regimes. The current diagnostics methods are imperfect hence new, more effective methods are still being sought. Component-resolved diagnostics (CRD) is one of them. CRD assesses sensitivity to individual allergen molecules using purified native or recombinant allergens. The present paper reviews the role of CRD in diagnosing CMA, as well as the benefits and limitations of its use, especially in predicting allergy development or acquiring immunotolerance. It examines the possibility of replacing the current gold diagnostic standard with component tests directed against specific milk proteins. In addition, CRD could be helpful in the evaluation of prognosis. However, CRD allows for improvement in clinical management, particularly of polysensitized subjects, there is still no cogent evidence that it offers more efficient CMA diagnostics than existing tests.

Patch testing with expired Indian patch test kits: Results of a pilot study

The reliability of patch testing with expired Indian standard patch test kits has been not evaluated before. Thirty adults (men:women 25:5) with allergic contact dermatitis were divided into three groups of ten patients each for patch testing by Finn chamber® method using Indian standard patch test kits having expiry in 2016, 2015 and 2014. The results were compared with those from a new kit with 2018 expiry. Ten patients in group-1, eight patients in group-2 and seven patients in group-3 developed positive reactions of identical intensities and mostly from identical allergens from all four kits. The major contact allergens eliciting positive reactions of identical intensities were parthenium in nine, five and three patients, colophony in four, one and zero patients, fragrance mix in three, three and one patients, thiuram mix in three, one and one patients, and paraphenylene diamine in two, one and three patients from group-1,-2, and -3, respectively. Small number of patients in each group remains the major limitation of the study. Whether or not these results can be extrapolated with patch test results from other similar patch test kits available across countries also needs confirmation. The patch test allergens can be used beyond labeled expiry dates but needs confirmation by a few large studies and using other available patch test kits. This is important as the relevance of patch test results for individual allergen in this scenario may remain debatable requiring careful interpretation.

MHTP, a synthetic alkaloid, attenuates combined allergic rhinitis and asthma syndrome through downregulation of the p38/ERK1/2 MAPK signaling pathway in mice

The combined allergic rhinitis and asthma syndrome (CARAS) is a chronic airway inflammation of allergic individuals, with a type 2 immune response. Pharmacotherapy is based on drugs with relevant side effects. Thus, the goal of this study was to evaluate the synthetic alkaloid, MHTP in the experimental model of CARAS. Therefore, BALB/c mice were ovalbumin (OVA) -sensitized and -challenged and treated with MHTP by intranasal or oral routes. Treated animals showed a decrease (p < 0.05) of sneezing, nasal rubbings, and histamine nasal hyperactivity. Besides, MHTP presented binding energy and favorable interaction for adequate anchoring in the histamine H1 receptor. MHTP treatment inhibited the eosinophil migration into the nasal (NALF) and the bronchoalveolar (BALF) fluids. Histological analysis showed that the alkaloid decreased the inflammatory cells in the subepithelial and perivascular regions of nasal tissue and in the peribronchiolar and perivascular regions of lung tissue. The MHTP treatment also reduced the pulmonary hyperactivity by decreasing the smooth muscle layer hypertrophy and the collagen fiber deposition in the extracellular matrix. The immunomodulatory effect of the alkaloid was due to the decrease of cytokines like IL-5 and IL-17A (type 2 and 3), TSLP (epithelial), and the immunoregulatory cytokine, TGF-β. These MHTP effects on granulocytes were dependent on the p38/ERK1/2 MAP kinase signaling pathway axis. Indeed, the synthetic alkaloid reduced the frequency of activation of both kinases independent of the NF-κB (p65) pathway indicating that the molecule shut down the intracellular transduction signals underlie the cytokine gene transcription.

Preparation of soybean β-conglycinin epitope antibody and its preliminary application in frozen surimi detection

Food allergy has become one of the food safety issues in the world. As a common source of food allergy, soybean poses a dietary risk to allergic individuals due to the presence of β-conglycinin, a main allergenic protein in soybean. Therefore, an efficient and sensitive detection method using highly specific antibody materials is necessary for the detection of allergens. In this study, we have used soybean major allergen β-conglycinin as research object, using analysis software such as DNAStar subroutine Protean, SOPMA server, etc. Three main subunits (α, α′ and β subunits) of β-conglycinin were sequenced. After a series of predictions, screenings and validations, we have obtained the most active epitope peptide with the sequence SNLNFLAFGINAENNQ from the β subunit. This epitope peptide was used to prepare rabbit-derived polyclonal antibodies. Using this antibody, we developed a quantum-dot-based fluorescent lateral flow immunoassay (LFIA) to detect β-conglycinin in frozen surimi. In this detection method, relevant conditions were optimized, and the detection limit was found to be 1.6 mg/g. In conclusion, the epitope peptide SNLNFLAFGINAENNQ was synthesized and using this epitope peptide as the immunogen, rabbit-derived polyclonal antibodies were prepared. A QD-based fluorescent LFIA detection method was developed for a simple, sensitive and specific detection of soybean major allergen β-conglycinin in surimi. This method is beneficial to the healthy development of the frozen surimi industry.

Structured diagnostic assessment of hand eczema in cleaning workers.

Hand dermatitis is a widespread problem among cleaners. In most cases, it is caused by a combination of wet work and contact with irritants, which can result in irritant (toxic) contact dermatitis. In some cases, the irritant contact eczema then evolves into allergic contact dermatitis, although not all cases of allergic contact dermatitis are preceded by irritant contact dermatitis. This mini-review proposes a two-step diagnostic algorithm based on patch testing, which can be used if allergic contact dermatitis is suspected in cleaning workers. As a first step, we recommend performing the DKG standard series (German Contact allergy research group, DKG), the DKG rubber series, both DKG "further fragrances" series as well as the DKG preservative and disinfectant series. If there are clear hints of an occupational contact dermatitis, the first step can also involve testing patients' own products alongside the standardized tests. In a second step (at the latest), if standardized tests do not suffice to identify the culprit allergen and there is well-founded suspicion, we recommend testing the patients' own products. If necessary, the second step can also include testing the individual contact allergens contained in the screening mixes that are part of the standard series.

Memory T helper cells identify patients with nickel, cobalt, and chromium metal allergy.

Patch testing is the gold standard for identifying culprit allergens in allergic contact dermatitis; however, it is laborious and positive reactions are difficult to quantitate. Development of complementary in vitro tests is, therefore, of great importance. This study aimed to improve the in vitro lymphocyte proliferation test (LPT) to detect allergic responses to nickel (Ni), cobalt (Co), and chromium (Cr). Twenty-one metal allergic patients with a positive patch test to Ni (n=16), Co (n=8), and Cr (n=3) and 13 controls were included. All were tested by a flow cytometric LPT. Metal-reactive cells were identified as T helper (Th) cells with high expression of the memory marker CD45RO. Skin-homing (cutaneous lymphocyte-associated antigen positive [CLA+]) Ni-reactive memory Th (Thmem hi ) cells identified individuals with a positive patch test for Ni with 100% sensitivity (95% confidence interval [CI] 81%-100%) and 92% specificity (95% CI 67%-100%). Moreover, Co-specific Thmem hi cells expressing CCR6 identified patients with a positive patch test for Co with 63% sensitivity (95% CI 31%-86%) and 100% specificity (95% CI 77%-100%). In Cr allergic individuals, Cr-reactive Thmem hi cells tended to increased CLA and CCR6 expression. Metal-reactive Th cells with high expression of CD45RO and coexpression of CLA and CCR6 improved the LPT, making it an attractive supplement to the patch test.

Comparison of Four Different Allergy Tests in Equine Asthma Affected Horses and Allergen Inhalation Provocation Test

Potential triggers for equine asthma are allergens from hay and straw dusts, mold spores and storage mites. The contribution of these environmental trigger factors to equine asthma is still largely uncertain. The aim of this study was to compare results of four allergy tests from healthy and asthma-affected horses, and to evaluate the clinical relevance of allergens tested positive via specific inhalation provocation test. Fifteen horses were classified using a clinical scoring system as asthmatic (n = 9) or control (n = 6). Four different allergy tests (functional in vitro test, intradermal test, Fc-epsilon receptor test, and ELISA for allergen-specific IgE) were compared. A histamine inhalation provocation test as positive control was performed in all horses and the interpleural pressure was measured. In addition, two individual allergens were chosen for the allergen inhalation provocation test based on the results of the allergy tests and inhaled in increasing concentrations, until signs of dyspnea occurred. None of the four allergy tests could differentiate reliably between controls and asthma-affected horses. There was no agreement among the results of the four allergy tests. The interpleural pressure results showed a large individual variability. A clear positive reaction on the allergen inhalation provocation test was only detected in two asthma-affected horses 6 hours after allergen inhalation with Aspergillus fumigatus and Cladosporium herbarum. In most cases a purely type I immediate reaction is unlikely to be involved in causing the clinical signs of equine asthma. Because of a delayed reaction after allergen provocation in two horses, the involvement of cell-mediated type III or IV hypersensitivity may be possible. As all allergy tests used in this study can only detect IgE-mediated hypersensitivity, these tests are probably not suitable for an etiological diagnosis of equine asthma.

Prevalence and trend of allergen sensitization in patients with nummular (discoid) eczema referred for patch testing: North American Contact Dermatitis Group data, 2001-2016.

Few studies have examined the relationship between nummular (discoid) eczema (NE) and allergic contact dermatitis (ACD). To examine trends, associations, and clinical relevance of ACD in patients with NE who were referred for patch testing. Retrospective analysis of 38 723 patients from the North American Contact Dermatitis Group. Overall, 748 patients (1.9%) were diagnosed with NE; 23.9% had a concomitant diagnosis of ACD. The prevalence of NE fluctuated over time between 2001 and 2016, with no overall change in prevalence in diagnosed NE. In multivariable logistic regression models, NE increased steadily with age and was associated with male sex and Asian and other race/ethnicity, and inversely associated with a history of atopic dermatitis (AD) and hay fever. Patients with NE had lower proportions of one or more positive allergic reactions and lower odds of a positive reaction in multiple individual allergens. The most commonly relevant allergens in patients with NE were formaldehyde 2.0% aq., methylisothiazolinone, quaternium 15, fragrance mix I, and propylene glycol. NE is a heterogeneous disorder with distinct subsets of lesional distributions and a profile of relevant allergens, especially formaldehyde and formaldehyde releasers. Nearly one in four patients with NE had ACD, supporting the role of patch testing in patients with NE.

Characterization of Innate Immune Responses to House Dust Mite Allergens: Pitfalls and Limitations.

Whereas house dust mite (HDM) allergy results from a dysregulated Th2-biased adaptive immune response, activation of innate immune signaling pathways is a critical prerequisite for the initiation of HDM sensitizations. Such innate sensing is mainly controlled by the airway epithelium and the skin. The resulting release of epithelial-derived proinflammatory cytokines and innate alarmins such as GM-CSF, IL-25, IL-33 and TSLP mediates the activation of ILC2 cells and cDCs to promote Th2-biased inflammation. Significant progress in the elucidation of HDM innate immune activation has been made in the past decade and highlighted key roles of the LPS/TLR4 axis, chitin-dependent pathways together with HDM protease allergens. However, the precise mechanisms by which HDM allergens are sensed by the innate immune system remain largely unknown. Such investigations are made difficult for several reasons. Among these are (1) the natural association of HDM allergens with immunostimulators from the mite exoskeleton as well as from environmental microorganisms/pollutants or endosymbiotic bacteria; (2) the purification of individual HDM allergens from extracts in sufficient amounts and devoid of any microbial and protein impurities; (3) the production of correctly folded recombinant HDM allergens which could display the same biological activity than their natural counterparts; (4) the accessibility to human epithelial samples with cellular heterogeneities and inter-donor variations; (5) the translation of experimental data from mouse models to humans is almost missing. The goal of the present mini-review is to emphasize some important limitations and pitfalls in the elucidation of innate immunostimulatory properties of HDM allergens.

Comparison of real-time PCR and ELISA for the detection of crustacean shellfish allergens

ABSTRACT Food allergies are a significant public health concern, and crustacean shellfish represent one of the major FDA regulated food allergens. Allergic individuals must avoid foods containing crustaceans, and this necessitates highly sensitive and accurate detection methods. Two of the major methods used are protein-based ELISA and DNA-based real-time PCR. In order to properly compare these very different methodologies, we used identical split samples for a side-by-side comparison and analysed them using four different real-time PCR methods and two different commercial ELISA kits. Three real-time PCR assays targeting the mitochondrial 12S genes of shrimp, crab, and lobster were compared to a commercial ELISA assay for total crustacean protein. A fourth real-time PCR assay targeting the tropomyosin gene of shrimp was compared to an ELISA assay for shrimp tropomyosin. All comparisons were carried out in two different food matrices: Manhattan clam chowder and fish sauce. PCR assays had a more broad dynamic range (0.1–106 mg/kg) as compared to ELISA (200–4000 mg/kg) and did not show matrix interference like ELISA. In cases where the ELISA assays did not have matrix interference, there was good qualitative agreement between PCR and ELISA.

Microarray-Based Allergy Diagnosis: Quo Vadis?

More than 30% of the world population suffers from allergy. Allergic individuals are characterized by the production of immunoglobulin E (IgE) antibodies against innocuous environmental allergens. Upon allergen recognition IgE mediates allergen-specific immediate and late-phase allergic inflammation in different organs. The identification of the disease-causing allergens by demonstrating the presence of allergen-specific IgE is the key to precision medicine in allergy because it allows tailoring different forms of prevention and treatment according to the sensitization profiles of individual allergic patients. More than 30 years ago molecular cloning started to accelerate the identification of the disease-causing allergen molecules and enabled their production as recombinant molecules. Based on recombinant allergen molecules, molecular allergy diagnosis was introduced into clinical practice and allowed dissecting the molecular sensitization profiles of allergic patients. In 2002 it was demonstrated that microarray technology allows assembling large numbers of allergen molecules on chips for the rapid serological testing of IgE sensitizations with small volumes of serum. Since then microarrayed allergens have revolutionized research and diagnosis in allergy, but several unmet needs remain. Here we show that detection of IgE- and IgG-reactivity to a panel of respiratory allergens microarrayed onto silicon elements is more sensitive than glass-based chips. We discuss the advantages of silicon-based allergen microarrays and how this technology will allow addressing hitherto unmet needs in microarray-based allergy diagnosis. Importantly, it described how the assembly of silicon microarray elements may create different microarray formats for suiting different diagnostic applications such as quick testing of single patients, medium scale testing and fully automated large scale testing.

Translation, adaption and validation of the total nasal symptom score (TNSS) for Lithuanian population

BackgroundAllergic rhinitis is one of the most prevalent allergic diseases worldwide which diagnosis is based on typical clinical signs and positive results of allergic tests. Selection and evaluation of treatment is based mainly on subjective symptoms. Objective measurement of patients’ complaints is necessary for proper documentation and follow-up. There are no short simple validated questionnaire assessing nasal symptoms in patients with allergic rhinitis in Lithuania. Total nasal symptoms score (TNSS) is a brief questionnaire which evaluate the severity of main symptoms of allergic rhinitis widely used in different countries. Our aim was to translate the TNSS in the Lithuanian language and to validate it.MethodsProspective cross-cultural adaption and validation study was performed. Linguistic validation of TNSS was performed and validity and reliability were assessed. Patients with chronic allergic and non-allergic rhinitis and healthy individuals were included in this study. Patients had to complete translated version of TNSS. Patients with allergic rhinitis additionally were asked to fill Rhinoconjunctivitis Quality of Life Questionnaire (RQLQ).ResultsSeventy-six individuals were involved into the study: 16 with non-allergic rhinitis (NAR) (21.1%), 49 with allergic rhinitis (AR) (64.5%) and 11 healthy individuals (14.5%). Cronbach’s α was 0.87. TNSS score was significantly higher in patients with NAR and AR compared with healthy individuals (3.56 ± 2.28 vs. 4.28 ± 2.46 vs. 0.27 ± 0.91). Positive significant correlation was found between TNSS score and RQLQ score (rs = 0.77, p < 0.01).ConclusionsThe Lithuanian version of the TNSS proved to be a valid instrument for assessing nasal symptoms in patients with allergic rhinitis.

Effect of roasting duration on the solubility, structure, and IgE-binding capacity of cashew nut proteins

Cashew nuts can induce severe allergic reactions in some allergic individuals. In this work, the solubility, structure and IgE-binding capacity of cashew proteins roasted for different durations were compared. The solubility of cashew nut proteins decreased after roasting. Ana o 3 and Ana o 2 was more thermally stable than Ana o 1. The analysis of the structure of cashew extracts by Fourier transform infrared spectroscopy and environmental scanning electron microscopy demonstrated that roasting reduced the contents of β-sheet and β-turn and led to the unfolding and aggregation of cashew protein. The IgE-binding capacity of cashew protein extracts seemed to decrease with the extension of roasting time.

A Quality Improvement Initiative to Improve Resident- Physician Practices Regarding Flu Vaccine Administration in Individuals with Egg Allergy

Individuals with any severity of egg allergy, including anaphylaxis, should receive the influenza vaccine annually per CDC guidelines. This recommendation has evolved over the past ten years. We performed a quality improvement initiative to assess and improve resident physician practices regarding flu vaccine administration in egg allergic individuals.

Allergenicity at component level of sub-pollen particles from different sources obtained by osmolar shock: A molecular approach to thunderstorm-related asthma outbreaks.

The so-called "thunderstorm asthma" (TA) is an uncommon but dramatic outbreak of asthma attacks occurring during a thunderstorm in the pollen and moulds season. Mechanisms which make the pollen able to enter the deeper airways and provoke severe asthma symptoms are still unclear. To test the hypothesis that sub-pollen particles (SPPs) originated from the rupture by an osmotic shock of pollen associated with TA contain allergens. After hydration, SPPs released from pollen grains of grass, pellitory, olive, cypress, ragweed and birch were isolated and determined by microscopy. Allergens were determined by in vitro ELISA inhibition tests indirectly using the sera from 10 polyreactive patients. An inhibition <50% was considered as negative, 50%-75% moderate and>75% complete. The inhibition experiments showed that the SPPs from birch and cypress were unable to inhibit serum IgE reactivity to Bet v 1 and Cup a 1, respectively. Ragweed SPPs inhibited ragweed pollen extract and Amb a 1 by 75.8±0.11% and 81.2±0.15%, respectively. Olive and pellitory SPPs retained almost the whole IgE-binding capability in all cases tested. Grass SPPs inhibited 32±0.06% of Lolium perenne Lol p 1 and 65% of Phleum pratense extracts, but results were highly variable for individual allergens (97.5%-0.03% for Phl p 2, 45.3±0.12% for Phl p 5, 24.7±0.22% for Phl p 6, and 38.3±0.2% for Phl p 1). Inhibition experiments confirm the hypothesis that SSPs obtained after the osmotic shock of pollen involved in TA, namely grass, pellitory and olive tree pollen, contain allergens and therefore they can induce severe asthma attacks during thunderstorms.

Profiling serum antibodies with a pan allergen phage library identifies key wheat allergy epitopes

Allergic reactions occur when IgE molecules become crosslinked by antigens such as food proteins. Here we create the ‘AllerScan’ programmable phage display system to characterize the binding specificities of anti-allergen IgG and IgE antibodies in serum against thousands of allergenic proteins from hundreds of organisms at peptide resolution. Using AllerScan, we identify robust anti-wheat IgE reactivities in wheat allergic individuals but not in wheat-sensitized individuals. Meanwhile, a key wheat epitope in alpha purothionin elicits dominant IgE responses among allergic patients, and frequent IgG responses among sensitized and non-allergic patients. A double-blind, placebo-controlled trial shows that alpha purothionin reactivity, among others, is strongly modulated by oral immunotherapy in tolerized individuals. AllerScan may thus serve as a high-throughput platform for unbiased analysis of anti-allergen antibody specificities.

Comparative proteomics of common allergenic tree pollens of birch, alder, and hazel.

BackgroundIn addition to known allergens, other proteins in pollen can aid the development of an immune response in allergic individuals. The contribution of the “unknown” protein allergens is apparent in phylogenetically related species where, despite of high homology of the lead allergens, the degree of allergenic potential can vary greatly. The aim of this study was to identify other potentially allergenic proteins in pollen of three common and highly related allergenic tree species: birch (Betula pendula), hazel (Corylus avellana) and alder (Alnus glutinosa).MethodsFor that purpose, we carried out a comprehensive, comparative proteomic screening of the pollen from the three species. In order to maximize protein recovery and coverage, different protein extraction and isolation strategies during sample preparation were employed.ResultsAs a result, we report 2500–3000 identified proteins per each of the pollen species. Identified proteins were further used for a number of annotation steps, providing insight into differential distribution of peptidases, peptidase inhibitors and other potential allergenic proteins across the three species. Moreover, we carried out functional enrichment analyses that, interestingly, corroborated high species similarity in spite of their relatively distinct protein profiles.ConclusionWe provide to our knowledge first insight into proteomes of two very important allergenic pollen types, hazel and alder, where not even transcriptomics data are available, and compared them to birch. Datasets from this study can be readily used as protein databases and as such serve as basis for further functional studies.

The Accuracy of Diagnostic Testing in Determining Tree Nut Allergy: A Systematic Review

Food allergy is most accurately diagnosed by a formal oral food challenge (OFC); however, it is time and labor intensive, risks the individual to severe reaction, and access is often a limiting step in the diagnostic process. This is compounded for tree nut allergy diagnosis as several OFCs may be required to determine allergy status to each individual tree nut. Accurate diagnosis using minimally invasive diagnostic tests in predicting clinical tree nut allergy is important to correctly identify those with potentially life-threatening reactions and to efficiently and safely tailor nut avoidance to only those nuts deemed allergic to enable less restricted diets and increased food choices for food allergic individuals. To conduct a systematic review on the diagnostic capacity of clinical tests (skin prick test, specific IgE, component-resolved diagnostics, and basophil activation test) to determine OFC-proven or clinical tree nut allergy. We searched 4 electronic databases (OVID Medline, Embase, Cochrane library, and PubMed) until May 2020. Eligible studies were categorized by type of tree nut and diagnostic test. A total of 27 studies assessed diagnostic accuracy to a specific tree nut. Overall, the accuracy of diagnostic testing was only reasonable, with 95% positive predictive values established in a small number of tree nuts. Cashew has best diagnostic accuracy, with the cashew component Ana o 3 being most predictive. At the other end of the spectrum, diagnostic testing of almond is poor and of limited clinical use. The systematic review highlights the limitations of our current diagnostic tools for tree nut allergy and highlights further areas for research. The unidirectionality of cross-reactivity between cashew/pistachio and walnut/pecan is described and can aid diagnosis. Using diagnostic algorithms such as those demonstrated for walnut/pecan and cashew/pistachio allergy, greater diagnostic accuracy and reduced number of OFCs may be achieved.