Assessment of the tolerance to lupine-enriched pasta in peanut-allergic children

Legume Allergens Pea, Chickpea, Lentil, Lupine and Beyond

PURPOSE OF THE REVIEW

In the last decade, an increasing trend towards a supposedly healthier vegan diet could be observed. However, recently, more cases of allergic reactions to plants and plant-based products such as meat-substitution products, which are often prepared with legumes, were reported. Here, we provide the current knowledge on legume allergen sources and the respective single allergens. We answer the question of which legumes beside the well-known food allergen sources peanut and soybean should be considered for diagnostic and therapeutic measures.

RECENT FINDINGS

These "non-priority" legumes, including beans, pea, lentils, chickpea, lupine, cowpea, pigeon pea, and fenugreek, are potentially new important allergen sources, causing mild-to-severe allergic reactions. Severe reactions have been described particularly for peas and lupine. An interesting aspect is the connection between anaphylactic reactions and exercise (food-dependent exercise-induced anaphylaxis), which has only recently been highlighted for legumes such as soybean, lentils and chickpea. Most allergic reactions derive from IgE cross-reactions to homologous proteins, for example between peanut and lupine, which is of particular importance for peanut-allergic individuals ignorant to these cross-reactions. From our findings we conclude that there is a need for large-scale studies that are geographically distinctive because most studies are case reports, and geographic differences of allergic diseases towards these legumes have already been discovered for well-known "Big 9" allergen sources such as peanut and soybean. Furthermore, the review illustrates the need for a better molecular diagnostic for these emerging non-priority allergen sources to evaluate IgE cross-reactivities to known allergens and identify true allergic reactions.

IgE-Mediated Legume Allergy: A Pediatric Perspective

Legumes are an inexpensive and essential protein source worldwide. The most consumed legumes include peanuts, soybeans, lentils, lupines, peas, common bean and chickpeas. In addition, the food industry is growing interested in expanding the use of legumes to partially replace or substitute cereals. Legumes were described to cause IgE-mediated allergies, and their growing use may also increase the incidence of allergy. The epidemiology of legume allergy varies by region; peanuts and soybeans are the legumes most involved in food allergies in Western countries, whereas lentils, peas, and chickpeas are reported as culprit allergens mainly in the Mediterranean area and India. This review, edited by the Italian Society of Pediatric Allergology and Immunology, summarizes the scientific literature on legume allergy in children and proposes a diagnostic workup and therapeutic approach.

Special Issue "Molecular and Cellular Advances in Atopic Diseases"

Atopic diseases, which currently affect around one billion people worldwide, are experiencing a rising prevalence [...].

Protein Concentration Affects the Food Allergen γ-Conglutin Uptake and Bacteria-Induced Cytokine Production in Dendritic Cells

γ-Conglutin (γ-C) from lupin seeds has been identified as a potent allergen with cross reactivity to peanuts. Here, we investigated how γ-C affected the response in bone marrow-derived dendritic cells (DCs) to bacterial stimuli. γ-C enhanced L. acidophilus NCFM (LaNCFM)-induced IL-12, IL-10, and IL-23 dose-dependently. In contrast, together with E. coli Nissle or LPS, γ-C reduced the production of IL-12 but not of IL-23 and IL-10. Enzyme-hydrolyzed γ-C also enhanced LaNCFM-induced IL-12 and IL-23 production. All preparations induced ROS production in the DCs. The mannose receptor ligands mannan and dextran and the clathrin inhibitor monodansylcadaverine partly inhibited the endocytosis of γ-C. Kunitz trypsin inhibitor and the scavenger receptor ligand polyG also enhanced LaNCFM-induced IL-12, indicating the involvement of receptors other than C-type lectin receptors. The endocytosis of labeled γ-C increased dose-dependently by addition of unlabeled γ-C, which coincided with γ-C's tendency to aggregate. Taken together, γ-C aggregation affects endocytosis and affects the cytokine production induced by gram-positive and gram-negative bacteria differently. We suggest that γ-C is taken up by the same mechanism as other food proteins but due to aggregation is present in higher concentration in the DCs. This could influence the resulting T-cell response in a microbial stimuli-dependent way.

High prevalence of lupin allergy among patients with peanut allergy: Identification of γ-conglutin as major allergen

BACKGROUND

Lupin is a protein-rich legume with a growing presence in the food market worldwide. With increased consumption, lupin allergy (LA) reports are also rising. Uncertainties exist on the cross-reactivity between peanut and lupin, the allergenic potential of different lupin species, and sensitization patterns among different populations.

OBJECTIVE

To evaluate the molecular basis of LA and to determine lupin allergens from 3 different species that may be involved in peanut allergy (PA) cross-reactivity.

METHODS

A total of 43 subjects with PA, those with LA, or controls without food allergy were evaluated with skin prick tests (SPTs) and specific IgEs (sIgEs). Lupin-sensitized subjects were offered a lupin oral food challenge (OFC). Immunoblots and enzyme-linked immunosorbent assays were performed on sera from lupin-sensitized subjects.

RESULTS

In this study, 44% of the PA subjects were confirmed to have LA by OFC. Anaphylaxis was the most frequent manifestation after lupin consumption, with a minimal eliciting dosage of 1 g lupin flour. There was no difference in lupin sIgE or SPT wheal size between lupin-sensitized and confirmed LA subjects or in the severity of symptoms among confirmed LA subjects. Sera from lupin-sensitized subjects uniformly reacted to all 3 different lupin species. Immunoblotting and enzyme-linked immunosorbent assays revealed immunoglobulin E binding to α- and γ-conglutin in all analyzed sera, whereas α- and β-conglutin recognition was variable.

CONCLUSION

Our findings reveal a high prevalence of LA among PA subjects, emphasizing lupin must be labeled as an allergen in foods. Owing to high variability in lupin-sIgE and lupin-SPT results, LA diagnosis may require OFC. In our population, γ-conglutin is the major allergen of lupin.

Recent advances in the management of nut allergy

Peanut/tree nut allergy is common and has been associated with particularly severe reactions. Epidemiological data have shown that the prevalence ranges between 0.05% and 4.9% for tree nut and between 0.5% and 3% for peanut. These large variations can be explained by differences in the age of included patients and the geographical region. In addition, the food consumption modality (ie, raw versus roasted) plays a major role, as heat treatment has the capacity to modify the allergenicity of nuts and legumes. Nut allergies tend to persist into adulthood and consequently have a high impact on quality of life.

Recently, it has been demonstrated that a significant proportion of nut allergic patients are able to tolerate other nuts. As opposed to the avoidance of all nuts, this approach is currently proposed in several tertiary allergy centers. However, diagnosis of nut allergy is particularly difficult due to co-sensitization leading to high rate of false positive skin prick tests and/or specific IgE to whole allergen extracts. The use of component resolved diagnosis leads to major improvement of diagnosis, particularly to distinguish between primary and secondary nut allergies. The basophil activation test has been suggested to be useful but is still used mainly as a research tool. Thus, diagnosis remains mainly based on the oral food challenge, which is considered as the gold standard.

Regarding treatment, avoidance remains the cornerstone of management of nut allergy. Oral immunotherapy is increasingly proposed as an alternative management strategy.

Adult and Pediatric Food Allergy to Chickpea, Pea, Lentil, and Lupine: A Scoping Review

BACKGROUND

Nonpriority legume allergies, which include chickpea, pea, lentil, and lupine, are frequently implicated in severe allergic reactions. Yet, studies on public health knowledge and educational needs are near-absent.

OBJECTIVE

To summarize what is known from the existing literature about nonpriority legume food allergy.

METHODS

Eligible, original research articles reported on both nonpriority legume food allergy and 1 or more of prevalence, burden, food labeling information, or current education strategies. Screening was performed by 2 independent reviewers. Conflicts were discussed and if consensus could not be reached, a third reviewer was consulted.

RESULTS

Of the 8976 titles identified, 47 were included subsequent to full-text screening. Most studies identified focused on prevalence, and were conducted in Europe, with additional studies from Asia, and North America. Although we defined burden quite broadly, few studies addressed the burden of nonpriority legume food allergens. Moreover, no studies addressed labeling or educational needs for these allergens.

CONCLUSIONS

Our review of the literature found current research focused on the prevalence of nonpriority legume allergy with significant gaps regarding burden, allergen labeling, and education strategies. To this end, further research on these aspects of nonpriority legume allergy is warranted.

Lupine allergens: Clinical relevance, molecular characterization, cross-reactivity, and detection strategies

Lupine is commonly utilized as a technological food and ingredient in a great variety of processed products (snacks, bakery, meat, and dairy products) principally owing to its nutritional value and technological properties. However, its ingestion, even at trace amounts (in the range of mg protein per kg of food), can lead to severe adverse reactions in allergic individuals. Lupine belongs to the Leguminosae family, having the conglutins (α-, β-, δ-, and γ-) as allergens, among other proteins. Cross-sensitization of lupine-sensitized individuals with other legume species, mainly peanut, can occur, but the associated clinical reactivity is still unclear. The protection of the sensitized individuals should depend on an avoidance diet, which should rely on the compliance of food labeling and, as such, on their verification by analytical methods. Food processing, such as heat treatments, has an important influence on the structural properties of lupine proteins, altering their detectability and allergenicity. In this review, different aspects related with lupine allergy are described, namely, the overall prevalence, clinical relevance, diagnosis, and treatment. The characterization of lupine allergens and their potential cross-reactivity with other legumes are critically discussed. The effects of food matrix, processing, and digestibility on lupine proteins, as well as the available analytical tools for detecting lupine at trace levels in foods, are also herein emphasized.

Personalized Nutrition Approach in Food Allergy: Is It Prime Time Yet?

The prevalence of food allergy appears to be steadily increasing in infants and young children. One of the major challenges of modern clinical nutrition is the implementation of individualized nutritional recommendations. The management of food allergy (FA) has seen major changes in recent years. While strict allergen avoidance is still the key treatment principle, it is increasingly clear that the avoidance diet should be tailored according to the patient FA phenotype. Furthermore, new insights into the gut microbiome and immune system explain the rising interest in tolerance induction and immunomodulation by microbiota-targeted dietary intervention. This review article focuses on the nutritional management of IgE mediated food allergy, mainly focusing on different aspects of the avoidance diet. A personalized approach to managing the food allergic individual is becoming more feasible as we are learning more about diagnostic modalities and allergic phenotypes. However, some unmet needs should be addressed to fully attain this goal.

Allergy to Peanut, Soybean, and Other Legumes: Recent Advances in Allergen Characterization, Stability to Processing and IgE Cross-Reactivity

Peanut and soybean are members of the Leguminosae family. They are two of the eight foods that account for the most significant food allergies in the United States and Europe. Allergic reactions to other legume species can be of importance in other regions of the world. The major allergens from peanut and soybean have been extensively analyzed and members of new protein families identified as potential marker allergens for symptom severity. Important recent advances concerning their molecular properties or clinical relevance have been made. Therefore, there is increasing interest in the characterization of allergens from other legume species such as lupine, lentil, chickpea, green bean, or pea. As legumes are mainly consumed after thermal processing, knowledge about the effect of such processing on the allergenicity of legumes has increased during the last years. In the present review, recent advances in the identification of allergens from peanut, soybean, lupine, and other legume species are summarized and discussed. An overview of the most recently described effects of thermal processing on the allergenic properties of legumes is provided and the potential IgE cross-reactivity among members of the Leguminosae family is discussed.

Lupin and Other Potentially Cross-Reactive Allergens in Peanut Allergy

PURPOSE OF REVIEW

The presence of IgE cross-reactivity between peanut allergens and allergens from other legumes and tree nuts has been demonstrated, but the identification of the involved individual allergens is still limited. The aim of this review is to describe new allergenic findings, of potential relevance for cross-reactivity among peanut and lupin.

RECENT FINDINGS

Seventeen allergens of peanut have been included in the official allergen nomenclature database to date. Lupin sensitization has been observed in 15-20% of individuals with known peanut allergy, The majority of lupin seed proteins are comprised of α-conglutins (legumin-like) and β-conglutins (vicilin-like), and to a lesser extent γ-conglutins (vicilin-like) and δ-conglutins (2S albumins). Several molecules may fuel peanut-lupin cross-reactivity. Awareness among physicians and general public could avoid unexpected allergic reactions. However, these do not appear frequent and no data suggest a precautionary labelling of lupin in foods.

Preacutionary labelling of cross-reactive foods: The case of rapeseed

Food allergic individuals are exposed to unnecessary dietary restrictions due to precautionary food allergy labelling (PFAL). Two forms of PFAL exist: type I identifies the possible presence of allergenic contaminaion in foods ('may content…'), type II indicates as potentially dangerous ingredients or contaminants that do no belong to official list of food allergens. PFAL type II is based on the fear of cross-reactivity with foods belonging to that list. PFAL type II is less known, but may be tempting for the legal offices of food companies, for clinicians in a 'defensive medicine' key, and even for legislators. We identify here a case of PFAL type II, allergy to rapeseed (belonging to the family of Brassicaceae). Increasingly used for their nutritional and nutraceutic value in asthma prevention, rapeseed has been indicated by regulatory authorities in Canada and Europe as potential cross-reactor with mustard. In this review, we provide the elements for a risk assessment of cross-reactivity of rapeseed/mustard allergy in the general population both clinically and from the point of view of the molecular allergy. Three findings emerge: 1. Allergic reactions to rapeseed are exceptional 2. The allergens identified in rapeseed and mustard are similar, but not identical 3. Reactions to rapeseed have never been described in mustard-allergic patients. On the ground of existing evidence, a precautionary labeling for rapeseed as potentially dangerous for patients allergic to mustard is not justified. In the interest of patients with multiple food allergy, PFAL type II must be avoided.

The future of lupin as a protein crop in Europe

Europe has become heavily dependent on soya bean imports, entailing trade agreements and quality standards that do not satisfy the European citizen's expectations. White, yellow, and narrow-leafed lupins are native European legumes that can become true alternatives to soya bean, given their elevated and high-quality protein content, potential health benefits, suitability for sustainable production, and acceptability to consumers. Nevertheless, lupin cultivation in Europe remains largely insufficient to guarantee a steady supply to the food industry, which in turn must innovate to produce attractive lupin-based protein-rich foods. Here, we address different aspects of the food supply chain that should be considered for lupin exploitation as a high-value protein source. Advanced breeding techniques are needed to provide new lupin varieties for socio-economically and environmentally sustainable cultivation. Novel processes should be optimized to obtain high-quality, safe lupin protein ingredients, and marketable foods need to be developed and offered to consumers. With such an integrated strategy, lupins can be established as an alternative protein crop, capable of promoting socio-economic growth and environmental benefits in Europe.

Skin prick test reactivity to lupin in comparison to peanut, pea, and soybean in atopic and non-atopic German subjects: A preliminary cross-sectional study

The increasing use of lupin in food processing poses a problem of potential (cross-)allergic reactions. To evaluate the prevalence of sensitization to lupin in comparison to that of other legumes skin prick tests were performed with lupin, pea, peanut, and soybean in atopic (n = 81) and non-atopic (n = 102) German adults. Of these 183 subjects, 20 subjects had to be excluded due to invalid skin prick tests (reaction to histamine <3 mm or to sodium chloride >2 mm). Thus, skin prick tests of 163 subjects were included in final analyses. Of 163 subjects, 18 had a positive reaction to at least one legume tested. Overall skin prick test reactivity was different among non-atopic and atopic subjects (P = 0.005). Altogether, six subjects (4%) were sensitized to lupin, 12 (7%) to pea, 5 (3%) to peanut, and 8 (5%) to soybean. Two (2%) of the 92 non-atopic subjects and 4 (6%) of the 71 atopic subjects had a positive skin prick test to lupin. Of the 6 subjects sensitized to lupin, 3 (50%) were also sensitized to pea, 3 (50%) to peanut, and 5 (83%) to soybean. In conclusion, the prevalence rates of lupin sensitization were comparable to or even lower than those of pea, peanut, and soybean. To date, lupin allergy is suspected to be relatively uncommon in the overall German population since lupin sensitization occurred in only 2% of non-atopic subjects. However, there is a clear risk of a lupin allergy in predisposed subjects, since the frequency of lupin sensitization was 6% in atopic subjects. In particular, subjects with existing sensitization or allergy to other legumes are at higher risk for a sensitization or allergy to lupin due to cross-reactivity.

In-depth glycoproteomic characterization of γ-conglutin by high-resolution accurate mass spectrometry

The molecular characterization of bioactive food components is necessary for understanding the mechanisms of their beneficial or detrimental effects on human health. This study focused on γ-conglutin, a well-known lupin seed N-glycoprotein with health-promoting properties and controversial allergenic potential. Given the importance of N-glycosylation for the functional and structural characteristics of proteins, we studied the purified protein by a mass spectrometry-based glycoproteomic approach able to identify the structure, micro-heterogeneity and attachment site of the bound N-glycan(s), and to provide extensive coverage of the protein sequence. The peptide/N-glycopeptide mixtures generated by enzymatic digestion (with or without N-deglycosylation) were analyzed by high-resolution accurate mass liquid chromatography-multi-stage mass spectrometry. The four main micro-heterogeneous variants of the single N-glycan bound to γ-conglutin were identified as Man2(Xyl) (Fuc) GlcNAc2, Man3(Xyl) (Fuc) GlcNAc2, GlcNAcMan3(Xyl) (Fuc) GlcNAc2 and GlcNAc 2Man3(Xyl) (Fuc) GlcNAc2. These carry both core β1,2-xylose and core α1-3-fucose (well known Cross-Reactive Carbohydrate Determinants), but corresponding fucose-free variants were also identified as minor components. The N-glycan was proven to reside on Asn131, one of the two potential N-glycosylation sites. The extensive coverage of the γ-conglutin amino acid sequence suggested three alternative N-termini of the small subunit, that were later confirmed by direct-infusion Orbitrap mass spectrometry analysis of the intact subunit.

Detectability of lupine seeds by ELISA and PCR may be strongly influenced by potential differences between cultivars

Accurate methods for allergen detection are needed for the verification of allergen labeling and the avoidance of hidden allergens. But systematic data on the influence of different cultivars of allergenic crop species on their detectability in enzyme-linked immunosorbent assay (ELISA) and polymerase chain reaction (PCR) are lacking. As one example, seeds of 14 different cultivars of lupine (Lupinus albus, Lupinus angustifolius, Lupinus luteus) were investigated for total protein according to a Kjeldahl method, and for their relative quantitative detectability in three commercial lupine-specific ELISA tests and four lupine-specific PCR methods. Total Kjeldahl nitrogen allowed an accurate quantification of total protein. Relative differences in quantitative response between cultivars of 390-5050% and 480-13,600% were observed between ELISA kits and PCR methods, respectively. Hence, quantitative results of selected ELISA and PCR methods may be strongly influenced by the examined lupine cultivar.

Characterization of the sensitization profile to lupin in peanut-allergic children and assessment of cross-reactivity risk

BACKGROUND

Case reports of allergy to lupin, due to primary sensitization or cross-reactions with other legumes, are increasing as a consequence of the augmented use of lupin flour in bakery, pasta formulations and other food items. The main allergens that have been associated with the sensitization to lupin are α- and β-conglutins and, to a lesser extent, γ- and δ-conglutin, but no conclusive data are available so far. The aim of this study was to characterize the sensitization pattern to lupin in a group of 12 Italian children allergic to peanut and identify the specific lupin proteins involved in the cross-reactivity with peanut.

METHODS

The immunochemical cross-reactivity among peanut and lupin was evaluated by both in vitro immunoblotting and in vivo fresh food skin prick test (FFSPT).

RESULTS

The results showed that β-conglutin was recognized by cutaneous IgEs from 7/12 peanut-allergic children in FFSPT and serum IgEs from 5/12 in immunoblotting, while 4/12 and 8/12 patients tested positive to γ-conglutin in FFSPT and immunoblotting, respectively. No significant immunoreactive responses were observed to α- and δ-conglutins under non-reducing conditions, but they were bound in FFSPT by the sera of 5/12 and 3/12 patients, respectively.

CONCLUSION

In this group of allergic children, β-conglutin has been identified as the major lupin allergen involved both in vitro and in vivo cross-reactivity with peanut proteins. The role of γ-conglutin in the cross-reactivity between lupin and peanut proteins was also relevant and clear, despite the observed unspecificity of the immunoblotting responses.

Developments in the field of allergy in 2009 through the eyes of Clinical and Experimental Allergy

In 2009 the journal published in the region of 200 papers including reviews, editorials, opinion pieces and original papers that ran the full gamut of allergic disease. It is instructive to take stock of this output to determine patterns of interest and where the cutting edge lies. We have surveyed the field of allergic disease as seen through the pages of Clinical and Experimental Allergy (CEA) highlighting trends, emphasizing notable observations and placing discoveries in the context of other key papers published during the year. The review is divided into similar sections as the journal. In the field of Asthma and Rhinitis CEA has contributed significantly to the debate about asthma phenotypes and expressed opinions about the cause of intrinsic asthma. It has also added its halfpennyworth to the hunt for meaningful biomarkers. In Mechanisms the considerable interest in T cell subsets including Th17 and T regulatory cells continues apace and the discipline of Epidemiology continues to invoke a steady stream of papers on risk factors for asthma with investigators still trying to explain the post-second world war epidemic of allergic disease. Experimental Models continue to make important contributions to our understanding of pathogenesis of allergic disease and in the Clinical Allergy section various angles on immunotherapy are explored. New allergens continue to be described in the allergens section to make those allergen chips even more complicated. A rich and vibrant year helpfully summarized by some of our associate editors.

IgE-mediated cross-reactivity among leguminous seed proteins in peanut allergic children

The immunological cross-reactivity among major protein- and oil-crops, including lupin, lentil, pea, peanut, kidney bean and soybean, has been studied by a combination of in vitro and in vivo experimental approaches: SDS-PAGE separations of legume protein extracts and immuno-blot revelations with 12 peanut-sensitive subjects' sera, Immuno-CAP and Skin Prick tests on the same subjects. The immuno-blotting data showed a wide range of IgE-binding responses both displayed by one subject towards different plant extracts and among subjects. Differences were both quantitative and qualitative. The prevalent responses of most subjects' sera were seen with peanut polypeptides, as expected, as well as with various polypeptides of the other legumes, the most recurrent of which were the basic subunits of the 11S globulins. The distribution of in vivo responses generally paralleled those obtained by in vitro approaches with strong responses elicited by peanut, lentil and pea protein extracts, especially by most sensitive subjects, thus providing a consistent overall set of results. In this work, the comparison of various approaches has allowed us to get an overall broad picture of the immunological cross-reactivities among proteins of widely used different seed species and to hypothesize the role of most conserved specific polypeptides.

Lupine, a source of new as well as hidden food allergens

The present review summarizes current knowledge about lupine allergy, potential sensitization routes, cross-reactions between lupine and other legumes, and the respective IgE-binding proteins. Since the 1990 s, lupine flour is used as a substitute for or additive to other flours, mostly wheat flour, in several countries of the EU. In 1994, the first case of an immediate-type allergy after ingestion of lupine flour-containing pasta was reported. Since then, the number of published incidents following ingestion or inhalation of lupine flour is rising. So far, the Lupinus angustifolius beta-conglutin has been designated as the allergen Lup an 1 by the International Union of Immunological Societies Allergen Nomenclature Subcommittee. Initially, publications focussed on the fact that peanut-allergic patients were at risk to develop anaphylaxis to lupine due to cross-reactivity between peanut and lupine. At present, however, the ratio between cases of pre-existing legume allergy (mostly peanut allergy) to de novo sensitization to lupine seed is nearly 1:1. Although in December 2006, lupine and products thereof were included in the EU foodstuff allergen list according to the Commission Directive 2006/142/EC amending Annex IIIA of Directive 2000/13/EC in order to prevent severe reactions caused by "hidden food allergens", the majority of patients and medical personnel are still not aware of raw lupine seed as potentially dangerous food allergen.