Peanut cross‐reacting allergens in seeds and sprouts of a range of legumes

Background Recently, peanut‐allergic patients have reported symptoms upon ingestion of bean sprouts produced from various legumes. Objective This study was designed to identify immunoreactivity to seeds and sprouts of legumes other than peanut in sera from peanut‐allergic patients. Methods Crude protein extracts of seeds and sprouts (comprising cotelydons and hypocotyls/epicotyls) of peanut, soybean, green pea, blue lupine, mung bean, alfalfa, broad bean, and azuki bean were prepared. The reactivity of sera from 10 peanut‐allergic patients to these extracts was analysed by indirect histamine release (HR), enzyme‐allergosorbent test (EAST), EAST inhibition, and Western blots. Skin prick tests (SPTs) were performed on the patients with fresh legume seeds as well as four commercial legume sprouts, and food challenges with soybean, pea, and lupine were performed on a subgroup of the patients. Results All legume seeds and commercial sprouts induced positive SPTs in some of the patients. Indirect HR experiments indicated an extensive co‐reactivity between peanut and the legumes, and cross‐reactivity was observed for soybean, pea, and lupine seeds as well as lupine hypocotyls in EAST inhibition experiments. Of the 16 protein extracts, soybean, pea, and lupine seed extracts produced visible bands in Western blots. Conclusion The symptoms reported by peanut‐allergic patients after legume sprout intake might be caused by cross‐reactivity of peanut‐specific antibodies. The intake of raw legume sprouts might cause symptoms in peanut‐allergic patients.     

Comparison of human IgE‐binding soya bean allergenic protein Gly m i with the antigenicity profiles of calf anti‐soya protein sera

In the food, particularly the feed, industry, large quantities of soya bean protein products are used for the formulation of end‐products destined for human or animal consumption. These basic ingredients and the final end products often have to fulfill specific requirements regarding the presence of antinutritional compounds (ANCs) and their allergenic potential. Therefore, a special need exists for the identification and characterization of ANCs and the causative factors behind allergy and hyper sensitivity. This paper describes the results of a comparative study of a previously identified unknown antigenic soya bean P22–25 protein with the first, recently described Gly m I (or P34) soya bean allergen. Sodium dodecyl sulphate polyacrylamide gel electrophoresis and Western blotting analysis were carried out using calf anti‐soya protein sera and a murine anti‐Gly m I (or P34) monoclonal antibody in order to detect the antigenic soya bean P22–25 protein and the allergen Gly m (or P34) respectively. The results showed that these proteins were different. In addition, a number of industrial soya bean products were analyzed for the presence of both apparent antigenicity (essentially ß‐conglycinin and P22–25) using calf anti‐soya protein sera and the allergen Gly m I (or P34), and both ß‐conglycinin, P22–25 and P34 could be detected to a varying extent in the products analyzed.     

Combined Immunomagnetic Separation and Detection of Salmonella enteritidis in Food Samples

A model system for immunochemical detection of Salmonella enteritidis has been developed, using immunomagnetic separation (IMS) with both commercially‐available and laboratory‐prepared antibodies, followed by an enrichment stage and end‐point detection by ELISA. IMS alone gave an average of 77% recovery of cells artificially inoculated into the food, and a range of 20–110% recovery, depending on food type. The combined model system (IMS‐ELISA) enables detection of either < 10 cells m^?1 whole egg extract (using overnight enrichment after IMS), or > 10 cells ml^?1 (3 h enrichment after IMS). Cross‐reactivity of antibodies with Citrobacter was decreased by using two different immunochemical steps: IMS with monoclonal antibody‐coated beads, and a ‘sandwich’ ELISA with polyclonal capture antibody and monoclonal detector antibody. Discussion is presented on the best food preparation method, optimal substrate type for the ELISA and on the potential of IMS.     

The analytical environmental immunochemical consortium

The Analytical Environmental Immunochemical Consortium (AEIC) is a relatively new organization, established with the aim of promoting the use of immunochemical methods as recognized analytical tools for food and environmental testing. The members of AEIC include immunoassay kit manufacturers, agricultural and basic chemical manufacturers, immunoassay equipment manufacturers and commercial, government and academic laboratories involved in the research and development of non‐clinical immunochemical technology.     

Unsuspected lupin allergens hidden in food

BACKGROUND: Lupin is a herbaceous plant from the legume family whose seed allergens usually have cross-reaction with peanut. Lupin flour is used in human nutrition because of its high nutritional and functional qualities. AIMS: The aim of this work was to detect non-specified lupin proteins contained in several manufactured foods. METHODS: Serum from a patient suffering anaphylactic episodes after ingestion of a certain brand of cookies and with oral allergy syndrome after eating chicken bouillon was used as a tracer. Lupin seeds and commercial food extracts were analyzed by SDS-PAGE, immunoblotting and immunoblotting inhibition. Lupin extract allergenicity after thermal processing was also analyzed. RESULTS: A lupin allergen with a molecular weight close to 14 kDa was detected in extracts from cookies, a chicken bouillon cube and a chicken dehydrated soup. CONCLUSIONS: The presence of unsuspected, hidden non-specified lupin sources in food labeling was demonstrated. According to the results of this study, it is important for food-allergic patients that food labels should declare all the components irrespective of their quantity.     

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. Cite this as: A. I. Sancho, K. Hoffmann‐Sommergruber, S. Alessandri, A. Conti, M. G. Giuffrida, P. Shewry, B. M. Jensen, P. Skov and S. Vieths, Clinical & Experimental Allergy, 2010 (40) 973–986.     

Concentrations of lead, cadmium, mercury and other elements in seeds of Lupinus mutabilis and of other legumes

Several species of legumes and varieties of lupins were examined for their heavy metal content in the seeds. Atomic absorption spectrometry was the main analytical tool. Validity and reproducibility of the results was checked by analyzing the same materials at two different laboratories performing the same technique. Additionally, inductively coupled plasma emission spectroscopy was applied. In grains of Lupinus mutabilis which constitute a traditional food in Andean populations, the following contents of heavy metals were determined: 0.10-0.25 microgram/g Cd; 0.5-1.6 microgram/g Pb; 0.10-0.15 microgram/g Hg. Seeds of other legumes contained 0.05-0.35 microgram/g Cd; 0.1-0.2 microgram/g Pb; 0.01-0.04 microgram/g Hg. The high lead content of lupins is easily reduced to one tenth by traditional extraction with boiling water. The mercury content, too, is decreased by this technique. The high manganese content of 1 300-1,400 micrograms/g of Lupinus albus compared to other legumes (25-37 micrograms/g) seems to be characteristic for this species and may be of nutritional significance. The comparison of the heavy metal contents of legume seeds of different origin and variety indicates a complex pattern of environmental and genetic factors that contribute to the specific metal contents of individual harvests. On the level of varieties the environmental factors (climate, soil, geology, agricultural techniques) seem to exhibit more important influences on the specific accumulation of heavy metals than genetic factors. In contrast, on the level of species or genera, the accumulation of heavy metals seems to be dominated by genetic factors rather than by environmental influences.     

A patient‐specific approach to develop an exclusion diet to manage food allergy in infants and children

Food allergy is becoming increasingly common in infants and young children. This article set out to explain the different factors that should be taken into account during an individualized allergy consultation: Foods to avoid and degree of avoidance, suitable alternatives, self‐management skills, co‐ and cross‐reactive allergens and novel allergens alongside the role of the industry in allergen avoidance, importance of nutritional aspects of the diet and the future directions that nutritional guidance make take. Allergy management advice should be individualized to provide a patient‐specific approach. Changes in the management of food allergies have in particular occurred in nut, milk and egg allergies over the past few years. There has also been a progressive increase in our understanding of cross‐reactivity between different foods and also food and aero‐allergens. A patient‐specific approach of allergen avoidance should consider factors relating to industry and the environment such as food and nutrition literacy, threshold levels, cross‐contact/contamination and safe eating away from home. Increasing migration and travel has also led to exposure of unfamiliar foods. As understanding improves on individual allergens and threshold levels, food labels and food labelling laws are affected. Allergy specialist dietitians should also keep up to date with the latest information on nutrition, the gut microbiome and the immune system to incorporate nutrition strategies in a dietetic consultation using an evidence‐based approach.     

Study of the complement system. General principles and perspectives

Measurement of complement in clinical medicine is traditionally based on the determination of CH50 and immunochemical and/or functional measurement of complement proteins C1q, factor B, C3 and C4. The interpretation of these measurements, as far as complement activation is concerned, can however be difficult as these tests do not allow to discriminate between consumption due to activation, hereditary deficiency, increased rate of synthesis or even hyposynthesis. This explains why their use as markers of evolutivity in diseases where complement activation is occurring has given variable results. New tests for complement activation have been more recently introduced. These are mainly the measurements of the anaphytotoxins, the degradation products of C3 and the membrane attack complex. As these tests reflect more directly complement activation, they may be more reliable markers. The immunochemical and functional measurements of C1-inhibitor are of special interest as they are the tests which allow definitive diagnosis of the hereditary angio-oedema. General principles for the interpretation of the different tests used to evaluate the complement system are presented and discussed.     

Viral modulation of antigen presentation: manipulation of cellular targets in the ER and beyond

Summary: Viruses that establish long‐term infections in their hosts have evolved a number of methods to interfere with the activities of the innate and adaptive immune systems. Control of viral infections is achieved in part through the action of cytotoxic T lymphocytes (CTLs) that recognize cytosolically derived antigenic peptides in the context of class I major histocompatibility complex (MHC) molecules. Viral replication within host cells produces abundant proteinaceous fodder for proteasomal digestion and display by class I MHC products. Tactics that disrupt antigen‐presentation pathways and prevent the display of peptides to CD8⁺ CTLs have been favored during the course of host‐virus co‐evolution. Viral immunoevasins exploit diverse cellular processes to interfere with host antiviral functions. The study of such viral factors has uncovered novel host proteins that assist these viral factors in their task and that themselves perform important cellular functions. Here, we focus on viral immunoevasins that, together with their cellular targets, interfere with antigen‐presentation pathways. In particular, we emphasize the intersection of the cellular quality‐control machinery in the endoplasmic reticulum with the herpesvirus proteins that have co‐opted it.     

The microbiology of alkaline-fermentation of indigenous seeds used as food condiments in Africa and Asia

Alkaline-fermented food condiments play an important role in the diets of many people in developing and a few developed countries. The rise in pH during production of these foods is due to the ability of the dominant microorganisms, Bacillus spp., to hydrolyze proteins into amino acids and ammonia. Studies have been undertaken which have investigated a number of these products like dawadawa, ugba, bikalga, kinema, natto, and thua-nao. In this review, current knowledge about the principal microbiological activities and biochemical modifications which occur during the processing of the alkaline condiments including nutritional, antimicrobial, and probiotic aspects are discussed. The current use of molecular biology methods in microbiological research has allowed unambiguous and more reliable identification of microorganisms involved in these fermentations generating sufficient knowledge for the selection of potential starter cultures for controlled and better production procedures for alkaline-fermented seeds condiments.     

Comparison of immunofluorescence method with histochemical and ELISA methods focusing on wheat protein detection in meat products

Gliadin is a major allergen causing allergies occurring also in meat products. Since wheat protein is used as a meat substitute to reduce cost of meat products. Sensitive consumers of these products are really threatened by food allergies in different allergic reaction. The objective of the study was to compare the histochemical, immunochemical (ALERT gliadin screening test) and immunofluorescence methods for the detection of wheat protein in model meat samples and meat products. The limit of detection for the ALERT gliadin screening test was 10?×?10⁴?mg?kg^?1 of addition, while the histochemical method demonstrated concentration of wheat protein already from 10?×?10³?mg?kg^?1, and the immunofluorescence method from the concentration of 20?mg?kg^?1. Comparison of the methods using McNemar’s test shows a statistically highly significant difference (p?=?.01) between the immunofluorescence method and ELISA and a statistically highly significant difference (p?=?.01) between the immunofluorescence and histochemical methods.     

Do chemosensory changes influence food intake in the elderly?

Food intake declines with age, and elderly individuals frequently report a decrease in appetite. Changes in chemosensory systems may partially explain this low intake. However, few data have directly linked changes in gustatory or olfactory function to food choice or intake. In two studies, taste perception and preference were unrelated to sodium chloride or sugar intakes. Olfaction may be more affected by age than taste. Olfactory dysfunction is associated with decreased enjoyment of food, and adding odors to foods can increase intake in some elderly individuals. The consumption of a varied diet depends in part on sensory-specific satiety (a decrease in the pleasantness of a food as it is consumed). Sensory-specific satiety diminishes with age, and this could be part of the explanation of why some elderly individuals have little variety in their diets. However, the impact of chemosensory deficits on nutritional status depends on a number of social and environmental factors. For example, despite their age, financially secure, free-living healthy older men and women consumed more varied diets than young adults. Changes in mechanisms regulating food intake can make it difficult for some elderly individuals to maintain energy balance. When chemosensory impairments are combined with changes in food intake regulatory mechanisms, the risk for nutritional deficiencies may be high. If we are to optimize food intake and nutritional status in the elderly, additional basic studies on how changes in chemosensory systems associated with aging affect food selection and intake are required.     

Nutritional treatment for inborn errors of metabolism: Indications, regulations, and availability of medical foods and dietary supplements using phenylketonuria as an example

Medical foods and dietary supplements are used to treat rare inborn errors of metabolism (IEM) identified through state-based universal newborn screening. These products are regulated under Food and Drug Administration (FDA) food and dietary supplement statutes. The lack of harmony in terminology used to refer to medical foods and dietary supplements and the misuse of words that imply that FDA regulates these products as drugs have led to confusion. These products are expensive and, although they are used for medical treatment of IEM, third-party payer coverage of these products is inconsistent across the United States. Clinicians and families report termination of coverage in late adolescence, failure to cover treatment during pregnancy, coverage for select conditions only, or no coverage. We describe the indications for specific nutritional treatment products for IEM and their regulation, availability, and categorization. We conclude with a discussion of the problems that have contributed to the paradox of identifying individuals with IEM through newborn screening but not guaranteeing that they receive optimal treatment. Throughout the paper, we use the nutritional treatment of phenylketonuria as an example of IEM treatment.     

Influence of thermal treatment of food on the immunochemical quantification of Gliadin

Gliadin quantification is of essential importance in foods for coeliac patients. Quantification of gliadins is affected by the thermal treatments usually employed in food processing. In order to study the influence of heating on immunochemical detection of gliadin, samples of wheat flour and dough were heated under different time‐temperature conditions (20 min at 100, 130 or 160°C). Ethanolic extracts (70%, ethanol/water, v/v) of treated samples were analyzed by electrophoresis in polyacrylamide gel at pH 3.1 (A‐PAGE) and the protein content quantified. Gliadin was measured by a competitive ELISA. Flour samples suffered no changes in the amount of protein extracted with 70% ethanol nor in the electrophoretic pattern of the extracts after treatments. A rise of 40% in immunochemical reactivity was observed when flour samples heated at 100 and 130°C were analyzed. Higher temperatures produced a drop in reactivity (20% below the original levels). When dough samples were analyzed, an important decrease in extracted protein was observed after the 130 and 160°C treatments. The electrophoretic pattern remained unchanged. A decrease of almost 90% in immunochemical reactivity was also observed after the 130 and 160°C treatments. Our results show that changes in the solubility and immunochemical reactivity of prolamins can lead to an over‐ or under‐estimation of the gliadin content depending on the thermal history and the nature of the sample.     

Physiological and psychosocial age-related changes associated with reduced food intake in older persons

Dietary intake changes during the course of aging. Normally an increase in food intake is observed around 55 years of age, which is followed by a reduction in food intake in individuals over 65 years of age. This reduction in dietary intake results in lowered levels of body fat and body weight, a phenomenon known as anorexia of aging. Anorexia of aging has a variety of consequences, including a decline in functional status, impaired muscle function, decreased bone mass, micronutrient deficiencies, reduced cognitive functions, increased hospital admission and even premature death. Several changes during lifetime have been implicated to play a role in the reduction in food intake and the development of anorexia of aging. These changes are both physiological, involving peripheral hormones, senses and central brain regulation and non-physiological, with differences in psychological and social factors. In the present review, we will focus on age-related changes in physiological and especially non-physiological factors, that play a role in the age-related changes in food intake and in the etiology of anorexia of aging. At the end we conclude with suggestions for future nutritional research to gain greater understanding of the development of anorexia of aging which could lead to earlier detection and better prevention.     

Comparison of different immunochemical methods for the detection and quantification of hazelnut proteins in food products.

Hazelnuts are widely used in the food industry owing to their nutritive value and taste. The amount of hazelnut present in a recipe is usually considered as a mark of quality. On the other hand, contamination of foods that normally do not contain hazelnuts is a threat for patients with a hazelnut allergy. For this reason, the availability of a method for the detection and quantification of hazelnuts in foods would be desirable. The objective of this study was to develop a method for the detection and quantification of minor amounts of hazelnut protein in food products that is potentially applicable for the food industry. Several immunochemical methods, e.g., immunoblotting and enzyme-linked immunosorbent assay (ELISA), were developed with antibodies from both hazelnut-sensitized patient sera and the sera of rabbits hyperimmunized with hazelnut protein. Immunoblotting appeared to be non-specific when the sera of patients were used as a source of antibodies. Using immunopurified antibodies from rabbits immunized with hazelnuts, immunoblotting became specific, but the sensitivity of this method was limited. Inhibition of IgE binding is a generally used test in clinical laboratories to establish contamination with hazelnuts. This approach is sensitive and specific, but not readily accessible for the food industry since patient serum is needed. Similar results in terms of sensitivity and specificity were obtained with a sandwich ELISA constructed with an immunopurified antibody from rabbits sensitized to hazelnuts. No substantial cross-reactivity with other nuts, legumes or other food constituents was observed, and concentrations as low as 5 ng/ml, corresponding to 1 ppm in food products, were detected. In a field test, several consumer products regarded to be free of hazelnuts were shown to contain traces of hazelnut. This sandwich ELISA constructed with immunopurified antibodies from rabbits sensitized with hazelnut protein is a sensitive and specific method to detect and quantify hazelnut and is useful in detecting trace contamination with hazelnut in various consumer products. Since this test does not require serum from patients, it is appropriate for use in the food industry.     

Effects of nutritional and environmental conditions on Sinorhizobium meliloti biofilm formation

Rhizobia are non-spore-forming soil bacteria that fix atmospheric nitrogen into ammonia in a symbiosis with legume roots. However, in the absence of a legume host, rhizobia manage to survive and hence must have evolved strategies to adapt to diverse environmental conditions. The capacity to respond to variations in nutrient availability enables the persistence of rhizobial species in soil, and consequently improves their ability to colonize and to survive in the host plant. Rhizobia, like many other soil bacteria, persist in nature most likely in sessile communities known as biofilms, which are most often composed of multiple microbial species. We have been employing in vitro assays to study environmental parameters that might influence biofilm formation in the Medicago symbiont Sinorhizobium meliloti. These parameters include carbon source, amount of nitrate, phosphate, calcium and magnesium as well as the effects of osmolarity and pH. The microtiter plate assay facilitates the detection of subtle differences in rhizobial biofilms in response to these parameters, thereby providing insight into how environmental stress or nutritional status influences rhizobial survival. Nutrients such as sucrose, phosphate and calcium enhance biofilm formation as their concentrations increase, whereas extreme temperatures and pH negatively affect biofilm formation.     

EAACI Food Allergy and Anaphylaxis Guidelines. Protecting consumers with food allergies: understanding food consumption,meeting regulations and identifying unmet needs

Individuals suffering from IgE‐mediated food allergy usually have to practise life‐long food allergen avoidance. This document aims to provide an overview of recent evidence‐based recommendations for allergen risk assessment and management in the food industry and discusses unmet needs and expectations of the food allergic consumer in that context. There is a general duty of care on the food industry and obligations in European Union legislation to reduce and manage the presence of allergens alongside other food hazards. Current evidence enables quantification of allergen reference doses used to set‐up reliable food safety management plans for some foods. However, further work is required to include a wider variety of foods and to understand the impact of the food matrix as well as additional factors which affect the progression and severity of symptoms as a function of dose. Major concerns have been raised by patients, carers and patient groups about the use of precautionary ‘may contain’ labelling to address the issue of unintended presence of allergens; these therefore need to be reconsidered. New and improved allergen detection methods should be evaluated for their application in food production. There is an urgent requirement for effective communication between healthcare professionals, patient organizations, food industry representatives and regulators to develop a better approach to protecting consumers with food allergies.     

Lipid transfer proteins and 2S albumins as allergens

Plant lipid transfer proteins, a widespread family of proteins, have been recently identified as important food allergens. Their common structural features, such as eight conserved cysteines forming disulfide bridges, basic isoelectric point and high similarity in amino acid sequence, are the basis of allergic clinical cross-reactivity. This has been demonstrated for the LTP allergens of the Prunoideae subfamily, whose similarity is about 95% as demonstrated for the purified allergens of peach, apricot, plum and apple. A relevant aspect is the existence of sequence homology of LTPs of botanically unrelated foods, as demonstrated for LTPs of maize and peach. A class of food allergens of well recognized clinical importance is that of seed storage 2S albumins. They have been identified in the most diffused edible seeds and nuts, such as mustard, sesame, Brazil nut, walnut and peanut. In particular, a strong correlation between IgE-binding to these proteins and food-induced anaphylaxis has been demonstrated for Brazil nut and sesame seeds.