Ses i 6, the sesame 11S globulin, can activate basophils and shows cross-reactivity with walnut in vitro

Cu2-xSe@Bi2MoO6 nanozyme-based immunoassay for the colorimetric detection of walnut allergen in foods

In the present study, we developed a nanozyme-based direct competitive immunoassay to detect walnut allergen (Jug r 4) in foods. Walnut monoclonal antibody (mAb) and Cu2-xSe@Bi2MoO6 nanocomposites were generated to form a signal probe by electrostatic adsorption. The nanocomposites had high peroxidase-like activity and could be stored at room temperature. The linear range of the optimized assay was 137.35 ± 0.14 to 3526.0 ± 4.53 μg/L with a limit of detection of 81.63 ± 0.89 μg/L. This method was validated by detecting walnut protein in bread, biscuits, and milk samples, providing recovery rates of 70.63-127.04 %. The fast and sensitive assay was suitable for the rapid detection of walnut allergen in foods.

Recent advance in sesame allergens: Influence of food processing and their detection methods

Sesame (Sesamum indicum L.) is a valuable oilseed crop with numerous nutritional benefits containing a diverse range of bioactive compounds. However, sesame is also considered an allergenic food that triggers various mild to severe adverse reactions (e.g., anaphylaxis). Strict dietary avoidance of sesame components is the best option to protect the sensitized consumers. Sesame or sesame-derived foods are always consumed after certain food processing operations, which would cause a considerable impact on the structure of sesame proteins, changing their sensitization capacity and detectability. In the review, the molecular structure properties, and immunological characteristics of the sesame allergens were described. Meanwhile, the influence of food processing techniques on sesame proteins and the relevant detection techniques used for the sesame allergens quantification are also emphasized critically. Hopefully, this review could provide valuable insight into the development and management for the new "Big Eight" sesame allergen in food industry.

Sesame as a source of food allergens: clinical relevance, molecular characterization, cross-reactivity, stability toward processing and detection strategies

Sesame is an allergenic food with an increasing allergy prevalence among the European/USA population. Sesame allergy is generally life-persisting, being the cause of severe/systemic adverse immune responses in sesame-allergic individuals. Herein, clinical data about sesame allergy, including prevalence, diagnosis, relevance, and treatments are described, with focus on the molecular characterization of sesame allergens, their cross-reactivity and co-sensitization phenomena. The influence of food processing and digestibility on the stability/immunoreactivity of sesame allergens is critically discussed and the analytical approaches available for their detection in foodstuffs. Cross-reactivity between sesame and tree nuts or peanuts is frequent because of the high similarities among proteins of the same family. However, cross-reactivity phenomena are not always correlated with true clinical allergy in sensitized patients. Data suggest that sesame allergens are resistant to heat treatments and digestibility, with little effect on their immunoreactivity. Nevertheless, data are scarce, evidencing the need for more research to understand the effect of food processing on sesame allergenicity modulation. The demands for identifying trace amounts of sesame in foods have prompted the development of analytical methods, which have targeted both protein and DNA markers, providing reliable, specific, and sensitive tools, crucial for the effective management of sesame as an allergenic food.

Sesame allergy: mechanisms, prevalence, allergens, residue detection, effects of processing and cross-reactivity

Sesame allergy is a serious public health problem and is mainly induced by IgE-mediated reactions, whose prevalence is distributed all over the world. Sesame has been included on the priority allergic food list in many countries. This review summarizes the mechanism and prevalence of sesame allergy. The characteristics, structures and epitopes of sesame allergens (Ses i 1 to Ses i 7) are included. Moreover, the detection methods for sesame allergens are evaluated, including nucleic-acid, immunoassays, mass spectrometry, and biosensors. Various processing techniques for reducing sesame allergenicity are discussed. Additionally, the potential cross-reactivity of sesame with other plant foods is assessed. It is found that the allergenicity of sesame is related to the structures and epitopes of sesame allergens. Immunoassays and mass spectrometry are the major analytical tools for detecting and quantifying sesame allergens in food. Limited technologies have been successfully used to reduce the antigenicity of sesame, involving microwave heating, high hydrostatic pressure, salt and pH treatment. More technologies for reducing the allergenicity of sesame should be widely investigated in future studies. The reduction of allergenicity in processed sesames should be ultimately confirmed by clinical studies. What's more, sesame may exhibit cross-reactivity with peanut and tree nuts.

Antibody Cross-Reactivity between Proteins of Chia Seed ( Salvia hispanica L.) and Other Food Allergens

Chia seeds are becoming increasingly common in Europe because of their functional and nutritional properties. Despite this, few studies have focused on the allergic potential and antibody cross-reactivity among storage proteins in chia seed and other plants. The aim of this study was to identify chia seed's immunoglobulin G (IgG) and immunoglobulin E (IgE) binding proteins ( Salvia hispanica L.) and to investigate the antibody cross-reactivity among its storage proteins and those of other seeds. Extracted chia seed proteins were separated by sodium dodecyl sulfate polyacrylamide gel electrophoresis (SDS-PAGE). Immunodetection was performed with commercial antibodies against sesame seed, hazelnut, and peanut and sera from 33 patients with a hazelnut allergy and five with a sesame allergy. Cross-reactivity of certain antibodies with storage proteins of chia seed, sesame seed, and hazelnut was assessed using an enzyme-linked immunosorbent assay (ELISA) inhibition, blot inhibition, and surface plasmon resonance (SPR) spectroscopy. IgG binding proteins were identified at molecular weight (MW) 70, 49, 34, 23, and 20 kDa by applying commercial antibodies. Furthermore, the interaction of chia proteins with sera from sesame-allergic patients led to identify IgE binding proteins at MW 49, 45, 31, 20, and 12 kDa, while IgEs in sera from hazelnut-allergic patients reacted with proteins at MW 300, 140, 49, 45, 31, 20, and 6 kDa. The results of ELISA inhibition and blot inhibition indicated chia seed proteins are similar to sesame seed and hazelnut proteins in the primary structure. The antisesame antibodies' binding to sesame proteins was more strongly inhibited by the chia globulin fraction (GLO) than the antihazelnut antibodies' binding to hazelnut proteins. SPR results confirmed the presence of IgG binding proteins in GLO and the high similarity of epitopes on globulins of chia seed and sesame seed. Thus, chia seed consumption might lead to cross-sensitization in patients with a sesame allergy.

Canis familiaris allergen Can f 7: Expression, purification and analysis of B cell epitopes in Chinese children with dog allergies

Dogs are a major source of indoor allergens. However, the prevalence of dog allergies in China remains unclear, especially in children. In the present study, Can f 7, a canine allergen belonging to the Niemann pick type C2 protein family, was selected to study its sensitization rate in Chinese children with dog allergies. The Can f 7 gene was subcloned into a pET‑28a vector and expressed in Escherichia coli BL21 (DE3) cells. Recombinant Can f 7 was purified by nickel affinity chromatography, identified by SDS‑PAGE electrophoresis, and had its allergenicity assessed by western blot, ELISA and basophil activation tests. Through a series of bioinformatical approaches, B‑cell epitopes, secondary structures, and 3 dimensional (3D) homology modeling of Can f 7 were predicted. The activity of the B cell epitopes was verified by ELISA. The recombinant Can f 7 showed a distinct band with a molecular weight of 14 kDa. Six of 20 sera from dog‑allergic children reacted positively to the Can f 7. Can f 7 induced an ~4.0‑fold increase in cluster of differentiation 63 and C‑C motif chemokine receptor R3 expression in basophils sensitized with the serum of dog‑allergic children compared with those of non‑allergic controls. The secondary structure analysis showed that Can f 7 contains 6 β‑sheets. Five B cell epitopes of Can f 7 were predicted, and two of these were confirmed by ELISA. These results indicate that Can f 7 is an important canine allergen in Chinese children and provide novel data for further research concerning the use of Can f 7 in the diagnosis and treatment of Chinese children with canine allergy symptoms.

Basophil Activation Test: Old and New Applications in Allergy

PURPOSE OF REVIEW

The basophil activation test (BAT) using flow cytometry has supplanted traditional methods of measuring basophil degranulation using histamine and other mediator release, and can be used for clinical applications as well as to explore the immune mechanisms of effector cell response to allergen. This review discusses the advancements made in clinical, diagnostic and laboratory research of allergy utilizing an ever-evolving BAT.

RECENT FINDINGS

Being an in vitro surrogate of the allergic reaction that happens in vivo in the sick patient, the BAT can be used to support the diagnosis of various allergic conditions, such as food, drug, respiratory and insect venom allergies, and the assessment of clinical response to allergen-specific immunotherapy and other immunomodulatory treatments. The BAT can also be used for research purposes to explore the mechanisms of allergy and tolerance at the level of the basophil, for instance by manipulating IgE and IgG and their receptors and by studying intracellular signalling cascade in response to allergen. This review covers the applications of the BAT to the clinical management of allergic patients and the increased understanding of the mechanisms of immune response to allergens as well as technological advancements made in recent years.

Sesame allergy: current perspectives

Sesame is an important global allergen affecting ~0.1% of the North American population. It is a major cause of anaphylaxis in the Middle East and is the third most common food allergen in Israel. We conducted a systematic review of original articles published in the last 10 years regarding the diagnosis and management of sesame allergy. Skin prick testing appears to be a useful predictor of sesame allergy in infants, although data are less consistent in older children and adults. The diagnostic capacity of serum-specific immunoglobulin E is poor, especially in studies that used oral food challenges to confirm the diagnosis. Double-blind, placebo-controlled food challenge thus remains the diagnostic gold standard for sesame allergy. The cornerstone of sesame allergy management is allergen avoidance, though accidental exposures are common and patients must be prepared to treat the consequent reactions with epinephrine. Novel diagnostic and treatment options such as component-resolved diagnostics, basophil activation testing, and oral immunotherapy are under development but are not ready for mainstream clinical application.

Basophil Degranulation Assay

Basophil degranulation assay has gained importance over the last decade in both diagnosis of food allergy and evaluation of progression of immunotherapy. This assay involves the identification and quantification of the expression of CD63 molecule on basophil membrane. CD63 is a marker of multivesicular bodies that is exposed to cell membrane during the process of degranulation in which the contents of basophil granules are released. This chapter describes the methodology for performing this assay.

Distinct Contributory Factors Determine Basophil-Allergen Sensitivity in Grass Pollen Rhinitis and in Anaphylactic Wasp Venom Allergy

BACKGROUND

We sought to determine whether basophil-allergen sensitivity could be transferred to donor basophils by passive IgE sensitisation in allergic rhinitis and anaphylactic Hymenoptera venom hypersensitivity.

METHODS

We studied 15 wasp venom-, 19 grass pollen- and 2 house dust mite-allergic patients, 2 healthy donors, and 8 wasp venom-allergic donors. In all subjects, we first evaluated the initial basophil response to wasp venom, grass pollen, or house dust mite allergen. Donor basophils were then stripped, sensitised with the different patients' serum IgE, and challenged with the corresponding allergen. The CD63 response of donor basophils was then compared with initial basophil responses.

RESULTS

In wasp venom-allergic subjects, the IgE transfer did not reflect the initial basophil-allergen sensitivity, because the venom IgE of subjects with high or low basophil sensitivity induced comparable responsiveness in healthy donor basophils. Furthermore, vice versa, when we sensitised the donor basophils of wasp venom-allergic individuals with different wasp venom or house dust mite IgE, we demonstrated that their response was predictable by their initial basophil allergen sensitivity. In the rhinitis allergy model, the IgE transfer correlated with the patients' initial basophil responsiveness because the grass pollen IgE of the subjects with high basophil allergen sensitivity induced significantly higher responsiveness of donor basophils than the IgE of subjects with initially low basophil allergen sensitivity.

CONCLUSIONS

Our results suggest that basophil allergen sensitivity evaluated by flow-cytometric CD63 analysis depends on two distinct contribution factors. In anaphylactic Hymenoptera allergy, the major factor was intrinsic cellular sensitivity, whereas in pollen allergy, the major factor was allergen-specific IgE on the cell surface.

Prevalence of food sensitization and probable food allergy among adults in India: the EuroPrevall INCO study

BACKGROUND

Data are lacking regarding the prevalence of food sensitization and probable food allergy among general population in India. We report the prevalence of sensitization and probable food allergy to 24 common foods among adults from general population in Karnataka, South India.

METHODOLOGY

The study was conducted in two stages: a screening study and a case-control study. A total of 11 791 adults in age group 20-54 were randomly sampled from general population in South India and answered a screening questionnaire. A total of 588 subjects (236 cases and 352 controls) participated in the case-control study involving a detailed questionnaire and specific IgE estimation for 24 common foods.

RESULTS

A high level of sensitization (26.5%) was observed for most of the foods in the general population, higher than that observed among adults in Europe, except for those foods that cross-react with birch pollen. Most of the sensitization was observed in subjects who had total IgE above the median IgE level. A high level of cross-reactivity was observed among different pollens and foods and among foods. The prevalence of probable food allergy (self-reports of adverse symptoms after the consumption of food and specific IgE to the same food) was 1.2%, which was mainly accounted for cow's milk (0.5%) and apple (0.5%).

CONCLUSION

Very high levels of sensitization were observed for most foods, including those not commonly consumed in the general population. For the levels of sensitization, the prevalence of probable food allergy was low. This disassociation needs to be further explored in future studies.

The Major Soybean Allergen Gly m Bd 28K Induces Hypersensitivity Reactions in Mice Sensitized to Cow's Milk Proteins

Reactions to soy have been reported in a proportion of patients with IgE-mediated cow's milk allergy (CMA). In this work, we analyzed if Gly m Bd 28K/P28, one of the major soybean allergens, is a cross-reactive allergen with cow milk proteins (CMP). We showed that P28 was recognized by IgE sera from CMA patients and activated human peripheral basophils degranulation. Moreover, IgE sera of mice exclusively sensitized to CMP recognized P28. Splenocytes from sensitized animals secreted IL-5 and IL-13 when incubated with CMP or soy proteins, but only IL-13 when treated with P28. In addition, a skin test was strongly positive for CMP and weakly positive for P28. Remarkably, milk-sensitized mice showed hypersensitivity symptoms following sublingual challenge with P28 or CMP. With the use of bioinformatics' tools seven putative cross-reactive epitopes were identified. In conclusion, using in vitro and in vivo tests we demonstrated that P28 is a novel cross-reactive allergen with CMP.

The development of a standardised diet history tool to support the diagnosis of food allergy

The disparity between reported and diagnosed food allergy makes robust diagnosis imperative. The allergy-focussed history is an important starting point, but published literature on its efficacy is sparse. Using a structured approach to connect symptoms, suspected foods and dietary intake, a multi-disciplinary task force of the European Academy of Allergy and Clinical Immunology developed paediatric and adult diet history tools. Both tools are divided into stages using traffic light labelling (red, amber and green). The red stage requires the practitioner to gather relevant information on symptoms, atopic history, food triggers, foods eaten and nutritional issues. The amber stage facilitates interpretation of the responses to the red-stage questions, thus enabling the practitioner to prepare to move forward. The final green stage provides a summary template and test algorithm to support continuation down the diagnostic pathway. These tools will provide a standardised, practical approach to support food allergy diagnosis, ensuring that all relevant information is captured and interpreted in a robust manner. Future work is required to validate their use in diverse age groups, disease entities and in different countries, in order to account for differences in health care systems, food availability and dietary norms.

Cross-reactivity between the soybean protein p34 and bovine caseins

Purpose

Soy-based formulas are widely used as dairy substitutes to treat milk allergy patients. However, reactions to soy have been reported in a small proportion of patients with IgE-mediated milk allergies. The aim of this work was to explore whether P34, a mayor soybean allergen, is involved in this cross-reactivity.

Methods

In vitro recognition of P34 was evaluated by immunoblotting, competitive ELISA and basophil activation tests (BAT) using sera from allergic patients. In vivo cross-reactivity was examined using an IgE-mediated milk allergy mouse model.

Results

P34 was recognized by IgE antibodies from the sera of milk allergic patients, casein-specific monoclonal antibodies, and sera from milk-allergic mice. Spleen cells from sensitized mice incubated with milk, soy or P34 secreted IL-5 and IL-13, while IFN-γ remained unchanged. In addition, the cutaneous test was positive with cow's milk proteins (CMP) and P34 in the milk allergy mouse model. Moreover, milk-sensitized mice developed immediate symptoms following sublingual exposure to P34.

Conclusions

Our results demonstrate that P34 shares epitopes with bovine casein, which is responsible for inducing hypersensitivity symptoms in milk allergic mice. This is the first report of the in vivo cross-allergenicity of P34.

The 11S globulin Sin a 2 from yellow mustard seeds shows IgE cross-reactivity with homologous counterparts from tree nuts and peanut

Background

The 11S globulin Sin a 2 is a marker to predict severity of symptoms in mustard allergic patients. The potential implication of Sin a 2 in cross-reactivity with tree nuts and peanut has not been investigated so far. In this work, we studied at the IgG and IgE level the involvement of the 11S globulin Sin a 2 in cross-reactivity among mustard, tree nuts and peanut.

Methods

Eleven well-characterized mustard-allergic patients sensitized to Sin a 2 were included in the study. A specific anti-Sin a 2 serum was obtained in rabbit. Skin prick tests (SPT), enzyme-linked immunosorbent assay (ELISA), immunoblotting and IgG or IgE-inhibition immunoblotting experiments using purified Sin a 2, Sin a 1, Sin a 3, mustard, almond, hazelnut, pistachio, walnut or peanut extracts were performed.

Results

The rabbit anti-Sin a 2 serum showed high affinity and specificity to Sin a 2, which allowed us to demonstrate that Sin a 2 shares IgG epitopes with allergenic 11S globulins from tree nuts (almond, hazelnut, pistachio and walnut) but not from peanut. All the patients included in the study had positive skin prick test to tree nuts and/or peanut and we subdivided them into two different groups according to their clinical symptoms after ingestion of such allergenic sources. We showed that 11S globulins contain conserved IgE epitopes involved in cross-reactivity among mustard, tree nuts and peanut as well as species-specific IgE epitopes.

Conclusions

The allergenic 11S globulin Sin a 2 from mustard is involved in cross-reactivity at the IgE level with tree nuts and peanut. Although the clinical relevance of the cross-reactive IgE epitopes present in 11S globulins needs to be investigated in further detail, our results contribute to improve the diagnosis and management of mustard allergic patients sensitized to Sin a 2.

Cloning and characterization of an 11S legumin, Car i 4, a major allergen in pecan

Among tree nut allergens, pecan allergens remain to be identified and characterized. The objective was to demonstrate the IgE-binding ability of pecan 11S legumin and characterize its sequential IgE-binding epitopes. The 11S legumin gene was amplified from a pecan cDNA library and expressed as a fusion protein in Escherichia coli. The native 11S legumin in pecan extract was identified by mass spectrometry/mass spectrometry (MS/MS). Sequential epitopes were determined by probing the overlapping peptides with three serum pools prepared from different patients' sera. A three-dimensional model was generated using almond legumin as a template and compared with known sequential epitopes on other allergenic tree nut homologues. Of 28 patients tested by dot blot, 16 (57%) bound to 11S legumin, designated Car i 4. MS/MS sequencing of native 11S legumin identified 33 kDa acidic and 20-22 kDa basic subunits. Both pecan and walnut seed protein extracts inhibited IgE binding to recombinant Car i 4, suggesting cross-reactivity with Jug r 4. Sequential epitope mapping results of Car i 4 revealed weak, moderate, and strong reactivity of serum pools against 10, 5, and 4 peptides, respectively. Seven peptides were recognized by all three serum pools, of which two were strongly reactive. The strongly reactive peptides were located in three discrete regions of the Car i 4 acidic subunit sequence (residues 118-132, 208-219, and 238-249). Homology modeling of Car i 4 revealed significant overlapping regions shared in common with other tree nut legumins.

Friday asthma crisis in the daughter of two bakers

The prevalence of sesame food allergy continues to increase worldwide. The diagnostic tools to confirm such allergy include skin prick tests, specific IgEs and food challenge. We report the case of a 7-year-old girl who presented recurrent episodes of wheezing and dyspnoea. After performing skin tests and evaluating specific IgEs we hypothesised an allergy to sesame. Our patient actually benefitted from avoiding any contact with sesame and sesame seeds. We confirmed our diagnosis through an inhalation food challenge. Further, by reviewing her personal history, we suspect inhalation was the mechanism in which the girl became sensitised to sesame.

Authentication of food allergen quality by physicochemical and immunological methods

Purified allergens are required to detect cross-contamination with other allergenic foods and to understand allergen interaction with other components of the food matrix. Pure allergens are also used for the diagnosis and treatment of food allergies. For example, serological methods are being developed to improve the quality of diagnosis, and to reduce the need for food challenge tests. In addition, recombinant allergens are being evaluated as candidate vaccines for safe and efficacious specific immunotherapy. Pure allergens are indispensable as reference materials for the calibration and standardization of methods between different laboratories and operators for risk assessment in the food industry. Therefore, there is a need for well-defined purified food allergens. In this context, a panel of 46 food allergens from plant and animal sources has been purified, from either the food sources or as recombinant forms, within the EU-funded EuroPrevall project. These allergens have been characterized by a battery of diagnostic tests demonstrating that they constitute an authentic, well-defined library of comparable quality. The review summarizes the applications, potentials and limitations of key techniques used for the characterization and authentication of these allergen preparations, with a special emphasis on protein purity and identity, folding, post-translational modifications and immunochemical properties. One key area identified is the development of powerful analytical techniques, such as mass spectrometry and nuclear magnetic resonance, to improve the authentication of allergens for routine applications in allergy management.

Lipocalin-type prostaglandin D synthase and egg white cystatin react with IgE antibodies from children with egg allergy

BACKGROUND

Ovalbumin, ovomucoid, ovotransferrin, lysozyme, and ovomucin are known to be major allergens found in egg white. Egg white protein is composed of over 30 proteins; many of which have neither been identified nor their allergenicities characterized. This study set out to analyze whether unknown proteins that bind to IgE antibodies in serum from patients with egg allergy exist in egg white.

METHODS

Diluted egg white proteins were separated by 2-dimensional (2-D) gel electrophoresis. Immunolabeling was performed on individual patient sera from 19 child patients with egg white allergy and 11 negative control subjects. Spots of egg white proteins that bound to the patients' IgE were identified by mass spectrometry-based proteomics.

RESULTS

Egg white proteins were separated into 63 spots. Twenty-five of the 63 reacted with egg allergy patients' sera, and 10 of the 25 reactive spots showed IgE-reactivity to controls as well. Specific bindings to the IgE from egg allergy patients were found in 15 spots; one of which was confirmed as ovotransferrin. Among the other 14 protein spots, egg white cystatin and lipocalin-type prostaglandin D synthase (L-PGDS) were newly identified proteins that reacted with IgE in patients with egg allergy.

CONCLUSIONS

We demonstrated that L-PGDS and cystatin reacted with serum IgE in patients with egg allergy. Our proteomics-based analysis in egg white gives a comprehensive map of proteins bound with IgE and should assist in enabling more accurate diagnoses and recommendations of desensitizing treatments for individual patients.

Linear IgE-epitope mapping and comparative structural homology modeling of hazelnut and English walnut 11S globulins

Allergic reactions to walnuts and hazelnuts can be serious. The 11S globulins (legumins) have been identified as important allergens in these and other nuts and seeds. Here we identify the linear IgE-binding epitopes of walnut and hazelnut 11S globulins, and generate 3D 11S globulin models to map the locations of the epitopes for comparison to other allergenic homologues. Linear IgE-epitope mapping was performed by solid-phase overlapping 15-amino acid peptides probed with IgE from pooled allergic human sera. Several walnut (Jug r 4) and hazelnut (Cor a 9) 11S globulin peptides with reactivity to patient IgE were identified. Comparative alignment with cashew (Ana o 2), peanut (Ara h 3), and soybean G1 (Gly m 6.0101) and G2 (Gly m 6.0201) allergenic homologues revealed several shared allergenic 'hot spots'. Homology modeling was performed based on the atomic structure of the soybean glycinin. Surface map comparisons between the tree nut and peanut homologues revealed structural motifs that could be important for IgE elicitation and binding and show that, contrary to predictions, the reactive epitopes are widely distributed throughout the monomeric subunits, both internally and externally, including regions occluded by quaternary subunit association. These findings reveal structural features that may be important to allergenicity and cross-reactivity of this protein class.

In vivo and T cell cross-reactivity between walnut, cashew and peanut

BACKGROUND

Examination of IgE cross-reactivity among nuts has been limited to in vitro experiments. Cross-reactivity studies of nuts at the T cell level are difficult to interpret because of the inability to determine which cellular responses are from a true sensitization and which are due to cross-reactivity. Using a mouse model in which the sensitizing nuts are controlled may provide novel methods to investigate in vivo and T cell cross-reactivity.

METHODS

C3H/HeJ mice were sensitized by intraperitoneal injection of cashew alone (monosensitized mice), or cashew plus walnut, utilizing alum as an adjuvant. Both groups underwent challenges to cashew, walnut and peanut, with subsequent monitoring of anaphylactic reactions. Anaphylactic antibodies were quantified by ELISA, and protein allergens were identified by Western blotting. Cellular responses were studied via splenocyte proliferation assay and measurement of secreted cytokines.

RESULTS

The monosensitized mice reacted to cashew and walnut during challenges, with significantly weaker reactions induced on challenge with peanut. Cross-reactive IgE to walnut and peanut were detected by ELISA, and the cross-reactive allergens were identified as vicilin proteins. In cellular assays, splenocytes from the monosensitized mice proliferated and produced IL-4 and IL-5 in response to cashew, walnut and peanut. The cashew- plus walnut-sensitized mice experienced stronger clinical reactions to walnut, recognized additional walnut allergens and secreted significantly more IL-4 and IL-5 in walnut-stimulated splenocyte assays compared to the monosensitized mice.

CONCLUSIONS

Cross-reactivity in vivo was found between cashew and walnut, while cross-reactivity among cashew, walnut and peanut was demonstrated at the T cell level.