Angioedema induced by inhalation of vapours from cooked white bean in a child

Predicting the allergenicity of legume proteins using a PBMC gene expression assay

BACKGROUND

Food proteins differ in their allergenic potential. Currently, there is no predictive and validated bio-assay to evaluate the allergenicity of novel food proteins. The objective of this study was to investigate the potential of a human peripheral blood mononuclear cell (PBMC) gene expression assay to identify biomarkers to predict the allergenicity of legume proteins.

RESULTS

PBMCs from healthy donors were exposed to weakly and strongly allergenic legume proteins (2S albumins, and 7S and 11S globulins from white bean, soybean, peanut, pea and lupine) in three experiments. Possible biomarkers for allergenicity were investigated by exposing PBMCs to a protein pair of weakly (white bean) and strongly allergenic (soybean) 7S globulins in a pilot experiment. Gene expression was measured by RNA-sequencing and differentially expressed genes were selected as biomarkers. 153 genes were identified as having significantly different expression levels to the 7S globulin of white bean compared to soybean. Inclusion of multiple protein pairs from 2S albumins (lupine and peanut) and 7S globulins (white bean and soybean) in a larger study, led to the selection of CCL2, CCL7, and RASD2 as biomarkers to distinguish weakly from strongly allergenic proteins. The relevance of these three biomarkers was confirmed by qPCR when PBMCs were exposed to a larger panel of weakly and strongly allergenic legume proteins (2S albumins, and 7S and 11S globulins from white bean, soybean, peanut, pea and lupine).

CONCLUSIONS

The PBMC gene expression assay can potentially distinguish weakly from strongly allergenic legume proteins within a protein family, though it will be challenging to develop a generic method for all protein families from plant and animal sources. Graded responses within a protein family might be of more value in allergenicity prediction instead of a yes or no classification.

Ranking of 10 legumes according to the prevalence of sensitization as a parameter to characterize allergenic proteins

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10 different legumes extracts could be ranked based on the variations in the prevalence of sensitization.

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Variations in the prevalence of sensitization allowed for ranking of 18 different individual legume proteins.

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Ranking can be used to select reference proteins to develop predictive assays for the assessment of the sensitizing potential of novel proteins.

Predicting the allergenicity of novel proteins is challenging due to the absence of validated predictive methods and a well-defined reference set of proteins. The prevalence of sensitization could be a parameter to select reference proteins to characterize allergenic proteins. This study investigated whether the prevalence of sensitization of legume extracts and proteins can indeed be used for this purpose. A random sample of suspected food-allergic patients (n=106) was therefore selected. 10 extracts (processed and non-processed) and 18 individual proteins (2S albumins, 7S and 11S globulins) from black lentil, blue and white lupine, chickpea, faba bean, green lentil, pea, peanut, soybean, and white bean were isolated and the prevalence of sensitization and the intensity of IgE binding were evaluated. The prevalence of sensitization ranged from 5.7 % (faba bean and green lentil) to 14.2 % (peanut). The prevalence of sensitization for individual legume proteins ranged from 0.0 % for albumin 1 (pea) to 15.1 %–17.9 % for Ara h 1, 2, 3, and 6 (peanut). The prevalence of sensitization correlated strongly with the intensity of IgE binding for individual proteins (p < 0.05, ρ = 0.894), for extracts no correlation was found. The discovered ranking can be used to select reference proteins for the development and validation of predictive in vitro or in vivo assays for the assessment of the sensitizing potential.

Legumes steam allergy in childhood: Update of the reported cases

In the past few decades, the prevalence of allergic diseases has deeply increased, with a key role played by food allergies. Legumes seem to play a major role towards the overall increase in the scenario of food allergy, since they are an appreciated source, consumed worldwide, due to their high protein content, variable amounts of lipids and for the presence of vitamins. In literature there are numerous descriptions of adverse reactions after ingestion of uncooked and cooked legumes. Nevertheless, cases of allergic reactions induced by inhaling vapours from cooking legumes have rarely been described. Herein the authors report an update of the literature data on allergic reactions caused by legume steam inhalation, underlying the possible pathogenic mechanism of these atopic events and the knowledge of literature data in paediatric age. The importance of this review is the focus on the clinical aspects concerning legume vapour allergy, referring to literature data in childhood.

Clinical features of legume allergy in children from a Mediterranean area

BACKGROUND

Lentils, chickpeas, beans, and peas are the most common consumed legumes in the Mediterranean area. However, there is little information about allergy to these legumes.

OBJECTIVES

To describe the clinical features of a Spanish pediatric population allergic to legumes (lentils, chickpeas, peas, white beans, and peanuts), to evaluate the clinical allergy to several legumes, and to determine which legume extract is most appropriate to use in the diagnosis of legume allergy by skin tests.

METHODS

Fifty-four children with allergic reactions after exposure to legumes were studied. The diagnosis of legume allergy was confirmed by positive skin prick test results with legume extracts and food challenges or a recent convincing history of severe reactions.

RESULTS

The onset of allergic reactions was at approximately the age of 2 years (median, 22 months). Skin prick test results were positive for at least 3 legumes in 38 children (70%). Positive results were more frequent to boiled extracts than to raw extracts in children with a positive oral challenge. Allergy to lentil was the most frequently diagnosed legume allergy (43 children [80%]), followed by allergy to chickpea (32 children [59%]). Oral challenges with more than 1 legume (median, 3 legumes) were positive in 37 children (69%). The most frequent induced symptoms on challenge were respiratory (rhinitis and/or asthma) and cutaneous.

CONCLUSION

In this population, lentils and chickpeas are the legumes that cause most allergic reactions, clinical allergy to more than 1 legume is common, and boiled legume extracts are most appropriate to discriminate between allergic and tolerant sensitized children.