Cross-allergenicity of peanut and lupine: the risk of lupine allergy in patients allergic to peanuts

Two-dimensional electrophoresis and western-blotting analyses with anti Ara h 3 basic subunit IgG evidence the cross-reacting polypeptides of Arachis hypogaea, Glycine max, and Lupinus albus seed proteomes

The allergenicity of seed storage proteins, the major components of edible legume seeds, may cause serious reactions in both children and adult population. Updated methodologies for evaluation of the activity of these proteins are needed. In this paper we used two-dimensional (2D) electrophoretic techniques to investigate the immuno-cross-reactivities of anti Ara h 3 basic subunit IgG to the seed proteomes of three legume species, namely, peanut, soybean, and lupin. The seed proteins, extracted with two different procedures, were separated by 2D electrophoresis, and the electrophoretic maps were analyzed by Western blot. In peanut proteome the antibodies strongly reacted with the 23 kDa polypeptides, corresponding to Ara h 3 basic isoforms, the antigen they were raised to, and three unidentified acidic polypeptides near 45 kDa. Remarkable cross-reactivities with lupin and soybean Ara h 3 homologous polypeptides and nonrelated proteins, namely, lupin conglutin gamma and soybean Bg7S, were detected. Therefore, these proteins may be regarded as new putative allergens. The present findings show the potentiality of 2D electrophoresis in the identification of food allergens and open the way to the traceability of the new cross-reacting proteins in the food chain.

Effects of extrusion, boiling, autoclaving, and microwave heating on lupine allergenicity

Lupine flour has been reported as a causative agent of allergic reactions. However, the allergenicity of lupine after thermal processing is not well-known. For this purpose, the allergenic characteristics of lupine seeds after boiling (up to 60 min), autoclaving (121 degrees C, 1.18 atm, up to 20 min and 138 degrees C, 2.56 atm, up to 30 min), microwave heating (30 min), and extrusion cooking were studied. The IgE-binding capacity was analyzed by IgE-immunoblotting and CAP inhibition using a serum pool from 23 patients with lupine-specific IgE. Skin testing was carried out in four patients. An important reduction in allergenicity after autoclaving at 138 degrees C for 20 min was observed. IgE antibodies from two individual sera recognized bands at 23 and 29 kDa in autoclaved samples at 138 degrees C for 20 min. Autoclaving for 30 min abolished the IgE binding to these two components. A previously undetected band at 70 kDa was recognized by an individual serum. Therefore, prolonged autoclaving might have an important effect on the allergenicity of lupine with the majority of patients lacking IgE reactivity to these processed samples.

A Case of Peanut Cross-Allergy to Lupine Flour in a Hot Dog Bread

BACKGROUND

In a case monitored by the Norwegian National Register for Severe Allergic Reactions to Food, a patient with peanut allergy experienced an allergic reaction after eating a particular brand of hot dog bread. The aim of this study was to identify the eliciting allergen.

METHODS

Extracts from the hot dog bread and reference material from peanut, lupine and lupine-fortified food products were analysed by immunochemical methods with patient serum and a new polyclonal anti-lupine antibody.

RESULTS

Evidence could be provided that the hot dog bread contained proteins from lupine but not from peanut.

CONCLUSION

Crossed peanut-lupine allergy can have clinical significance. A peanut-allergic patient reacted against hidden lupine protein in a hot dog bread. Presented with our results, the producer confirmed the use of lupine flour and changed the ingredient list.

Patients with anaphylaxis to pea can have peanut allergy caused by cross-reactive IgE to vicilin (Ara h 1)

BACKGROUND

Serologic cross-reactivity among legumes has been described; however, it is rarely clinically significant. In this study 3 patients with a history of anaphylaxis to pea are described who subsequently had symptoms after ingestion of peanut.

OBJECTIVE

We investigated whether the peanut-related symptoms were due to cross-reactivity between pea and peanut proteins.

METHODS

Peanut-related symptoms were documented according to case history or double-blind, placebo-controlled food challenge results. Skin prick tests were performed, and specific IgE levels were determined for pea and peanut with the CAP system FEIA. IgE-binding proteins in pea and peanut were identified by using immunoblot analysis. Cross-reactivity was studied by means of immunoblot and ELISA inhibition studies with whole extracts and purified allergens.

RESULTS

Peanut-related symptoms consisted of oral symptoms in all patients, with additional urticaria and dyspnea or angioedema in 2 patients. All patients had a positive skin prick test response and an increased IgE level to pea and peanut. Immunoblotting revealed strong IgE binding to mainly vicilin in pea extract and exclusively to Ara h 1 in crude peanut extract. Immunoblot and ELISA inhibition studies with crude extracts, as well as purified proteins, showed that IgE binding to peanut could be inhibited by pea but not or only partially the other way around.

CONCLUSION

Clinically relevant cross-reactivity between pea and peanut does occur. Vicilin homologues in pea and peanut (Ara h 1) are the molecular basis for this cross-reactivity.

Clinical features of cross-reactivity of food allergy caused by fruits

Fruits are increasingly recognized as a cause of food allergy. The wide cross-reactivity among these foods has been extensively studied. In this review we will focus on studies addressing the clinical relevance of cross-reactivity among fruits, the diagnostic management of patients complaining of reactions to multiple fruits, and adequate dietary recommendations.

Clinical update on peanut allergy

BACKGROUND

Peanut allergy is common, potentially severe, and there has been a recent surge in clinical investigation of this important food allergen.

OBJECTIVE

To provide the reader with a clinically oriented update on peanut allergy.

DATA SOURCES

English language articles were selected from PubMed searches (search terms: peanut allergy, food allergy, anaphylaxis) and selected abstracts with a bias toward recent (3 years) studies judged to have immediate, practical clinical implications.

RESULTS

Peanut allergy is an increasing problem in western diets that include this food. Both genetic and environmental factors influences the expression of this allergy. The at-risk subject is an atopic individual, with heightened risk for those with atopic dermatitis and/or other food allergies. The allergy is long-lived for most, may increase slightly in severity over time, but approximately 20% of young children will develop tolerance. Parameters that may identify the subset likely to achieve tolerance have been identified. Several large studies have determined laboratory parameters (skin tests, peanut-specific serum immunoglobulin E concentrations) with excellent predictive value (>95%) to diagnose current clinical reactivity or tolerance, although oral food challenges are necessary for a definitive diagnosis. Numerous practical lessons concerning management (avoidance, treatment, and prevention) have been identified.

CONCLUSIONS

Recent studies provide the clinician with an armament of improved diagnostic and treatment modalities for peanut allergy. Studies are underway that are likely to provide more definitive therapies in the near future.

Clinical implications of cross-reactive food allergens

As a consequence of the general increase in allergic sensitization, the prevalence of hypersensitivity reactions to multiple foods that share homologous proteins has become a significant clinical problem. A variety of these allergens conserved among plants (eg, profilin and lipid transfer proteins) and animals (eg, tropomyosin and caseins) have been characterized. Although studies with molecular biologic techniques have elucidated the nature of these ubiquitous allergens, clinical studies have lagged behind. The physician is called on to determine the risk of reaction to related foods among legumes, tree nuts, fish, shellfish, cereal grains, mammalian and avian food products, and a variety of other plant-derived foods that may share proteins with pollens, latex, and each other. Clinical evaluations require a careful history, laboratory evaluation, and in some cases oral food challenges. The pitfalls in the evaluation of food allergy-unreliable histories and limitations in laboratory assessment primarily caused by false-positive skin prick test responses/RAST results are magnified when dealing with cross-reactive proteins. This review focuses on the clinical data regarding cross-reacting food allergens with the goal of providing a background for improved risk assessment and a framework on which to approach these difficult clinical questions.

Food anaphylaxis in schools: evaluation of the management plan and the efficiency of the emergency kit

BACKGROUND

Children with severe food allergies can benefit from a personalized care project (PCP) in schools. The usefulness of the PCP and the residual risk of allergic emergencies are poorly appreciated. The objective was to evaluate the efficiency of the management plan and the training in the use of the emergency kit.

METHODS

A telephone survey using a detailed questionnaire was performed in 45 families whose children had been previously referred to the department. The distribution of disorders was as follows: asthma, 37.7%; atopic dermatitis and asthma, 28.8%; atopic dermatitis, 15.5%; angioedema and urticaria, 13.3%; and anaphylactic shock, 4.2%. Food allergy had been diagnosed in the 45 children by past history, and double-blind or single-blind, placebo-controlled food challenges (DBPCFCs, or SBPCFCs) with evidence of specific IgE. Exactly 75.5% of the children had peanut allergy. Multiple food allergies characterized 46.8% of the subjects. They had benefited from a strict elimination diet and a protocol for emergency care including a ready-to-use intramuscular epinephrine injection. A PCP had been requested by the School Public Health Service.

RESULTS

Thirty-nine PCPs were implemented (86.5% of the requests). They represented 63% of the PCPs for food allergy in the eastern region of France: one per 5800 school-age children. The retrospective period of evaluation was 25 months on average. The types of meals were very diverse, and medically acceptable in 83% of cases. The place where the emergency kit was stored in the school varied. Forty reactions occurred in 33% of the children (5/6 times in the absence of a PCP), asthma in 28%, shock in 1%, and immediate skin reactions in 11%. Reactions occurred at home in 78% of the subjects, and in school in 22% of the subjects. The cause of the reactions was not specifically known in 63% of cases. Twenty-seven percent of the reactions were linked to the ingestion of food allergens. In 10% of subjects, the reaction was due to a modification of ingredients by the food industry.

CONCLUSIONS

The frequency of respiratory symptoms during oral challenge tests was confirmed by the frequency of asthmatic reactions within the follow-up period. The role of hidden allergens and of misleading labeling validates the need for PCPs in the case of peanut and tree nut allergies, past history of severe reactions, multiple food allergies, reactions to a low dose in DBPCFCs, and asthmatic reactions to foods. This study provides encouraging data on the usefulness of PCPs and confirms the need for thorough instruction and training of the school staff in dealing with allergic emergencies. Addition of a beta-agonist spray to the emergency kit is suggested.

Occupational IgE-mediated allergy after exposure to lupine seed flour

The ingestion of lupine seed flour (LSF) has been reported as a cause of allergic reactions, particularly in patients sensitized to peanut, but there is little evidence of its allergenic potential after inhalation. We sought to evaluate the clinical and immunologic reactivity to lupine in employees working with this seed flour. An occupational history was obtained in 7 subjects (median age, 35 years) working with LSF at an agricultural research center. Three subjects (1, 6, and 7) reported work-related allergy symptoms immediately after being exposed to lupine. Skin prick test results with LSF extract were positive in these 3 patients with work-related symptoms. Moreover, lupine-specific IgE antibodies were detected in subjects 6 and 7. In subject 6, the controlled exposure to LSF elicited immediate naso-ocular symptoms without changes in FEV(1). In subject 7, a bronchial provocation with LSF extract elicited an immediate fall (25%) in FEV(1). Double-blinded, placebo-controlled LSF oral challenge results were positive in subjects 6 and 7. Immunologic reactivity to other legumes was detected in subjects 6 and 7, but specific inhalation testing and oral challenge results were negative. Thus, the inhalation of lupine flour could be an important cause of allergic sensitization in exposed workers and might give rise to occupational asthma and food allergy.

Diagnosis and management of childhood food allergy

The pediatrician plays a pivotal role in the initial diagnosis of food allergy. Alternative diagnoses are considered as a careful history, physical examination, and directed laboratory tests determine the type of adverse reaction and the responsible food. Through elimination diets in infants, appropriately selected tests for specific IgE, and, in some cases, supervised oral food challenges, a diagnosis is secured. Treatment consists of strict dietary elimination with provisions for emergency management of accidental ingestions. Referral to an allergist and dietitian is made as warranted by the severity and type of allergy and for follow-up for possible resolution of the allergy. The pediatrician also provides information to the family for the prevention of allergy in at-risk newborns. Future diagnostic tests and treatment modalities are likely to simplify the management of the food allergic child.

Peanut and tree nut allergy

Among foods causing allergic reactions in children, peanut (a legume) and tree nuts (ie, walnut, hazel nut, Brazil nut, pecan) have attracted considerable attention for several reasons. Allergies to these foods are common, frequently have an onset in the first few years of life, generally persist, and account for severe and potentially fatal allergic reactions. Furthermore, the ubiquity of these foods in the diet makes avoidance difficult and accidental ingestions, with reactions, common. This review discusses recent and emerging information on the prevalence, clinical characteristics, natural history, genetic basis, and current treatment of these allergies. In addition, recent advances in the molecular and immunologic characteristics of these allergens, and novel therapeutic options under investigation in animal models, are reviewed.

[Risk of serious acute asthma due to lupine flour associated with peanut allergy]

Lupine flour (lupinus albus), recently authorized in France in human food, cross-reacts with peanuts. We report a case of acute asthma in a patient with allergy to peanuts.

EXEGESIS

This patient has a severe allergy to peanuts, presenting as acute asthma. Skin prick-tests to raw and cooked lupine flour were positive. The level of specific-IgE (Allerbio, France) to lupine flour were high. Oral challenge test induced acute asthma at a dose of 965 mg of lupine flour. This quantity may be included in 100 g of bread.

CONCLUSION

This case report points out the fact that lupine flour is a high-risk allergen in patients presenting allergy to peanuts. It is necessary to evaluate the allergenic risk of new foods before their introduction into human daily food intake and to establish a network of allergy vigilance.