Allergenicity of 10 different apple varieties

BSACI guideline for the diagnosis and management of pollen food syndrome in the UK

Pollen food syndrome (PFS) is a highly prevalent food allergy affecting pollen-sensitized children and adults. Sufferers experience allergic symptoms when consuming raw plant foods, due to the homology between the pollen allergens and unstable proteins in these foods. The triggers involved can vary depending on the pollen sensitization, which in turn is affected by geographical location. The British Society of Allergy and Clinical Immunology (BSACI) Standards of Care Committee (SOCC) identified a need to develop a guideline for the diagnosis and management of PFS in the United Kingdom (UK). Guidelines produced by the BSACI use either the GRADE or SIGN methodology; due to a lack of high-quality evidence these recommendations were formulated using the SIGN guidelines, which is acknowledged to be less robust than the GRADE approach. The correct diagnosis of PFS ensures the avoidance of a misdiagnosis of a primary peanut or tree nut allergy or confusion with another plant food allergy to non-specific lipid transfer proteins. The characteristic foods involved, and rapid-onset oropharyngeal symptoms, mean PFS can often be diagnosed from the clinical history alone. However, reactions involving tree nuts, peanuts and soya milk or severe/atypical reactions to fruits and vegetables may require additional diagnostic tests. Management is through the exclusion of known trigger foods, which may appear to be simple, but is highly problematic if coupled with a pre-existing food allergy or for individuals following a vegetarian/vegan diet. Immunotherapy to pollens is not an effective treatment for PFS, and although oral or sublingual immunotherapy to foods seems more promising, large, controlled studies are needed. The typically mild symptoms of PFS can lead to an erroneous perception that this condition is always easily managed, but severe reactions can occur, and anxiety about the onset of symptoms to new foods can have a profound effect on quality of life.

Apple allergy: Causes and factors influencing fruits allergenic properties-Review

BACKGROUND

Apple tree fruits (Malus × domestica Borkh.) are a rich source of nutrients and nutraceuticals and are recommended as a part of the healthy, staple diet. However, apples could be also the cause of allergies including severe reactions. Allergies to fruits like apples are predominantly associated with pollinosis. In North and Central Europe, sensitisation to apples is caused mainly by cross-reactive birch pollen aeroallergen, whereas in the Mediterranean area of Europe, apple allergy is mostly associated with allergies to peach. The allergenicity of apples differ across cultivars but only a few varieties were studied. Some factors changing apples allergenicity were identified, including unmodifiable and potentially modifiable factors for example cultivation method, ripening stage and storage conditions.

AIM

This review presents current knowledge about the molecular basis of apple allergenicity and factors influencing its level.

CONCLUSIONS

Selecting cultivars with low potential of allergenicity, removing apple peel and heat treatment could reduce the risk of severe allergy reaction incidence and presumably can be used in birch pollen immunotherapy.

Relationship between Phenolic Compounds, Antioxidant Properties, and the Allergenic Protein Mal d 1 in Different Selenium-Biofortified Apple Cultivars (Malus domestica)

Notable parts of the population in Europe suffer from allergies towards apples. To address this health problem, the analysis of the interactions of relevant allergens with other substances such as phenolic compounds is of particular importance. The aim of this study was to evaluate the correlations between the total phenolic content (TPC), polyphenol oxidase (PPO) activity, antioxidant activity (AOA), and the phenolic compound profile and the content of the allergenic protein Mal d 1 in six apple cultivars. It was found that the PPO activity and the content of individual phenolic compounds had an influence on the Mal d 1 content. With regard to the important constituents, flavan-3-ols and phenolic acids, it was found that apples with a higher content of chlorogenic acid and a low content of procyanidin trimers and/or epicatechin had a lower allergenic potential. This is probably based on the reaction of phenolic compounds (when oxidized by the endogenous PPO) with proteins, thus being able to change the conformation of the (allergenic) proteins, which further corresponds to a loss of antibody recognition. When apples were additionally biofortified with selenium, the composition of the apples, with regard to TPC, phenolic profile, AOA, and PPO, was significantly affected. Consequently, this innovative agronomic practice seems to be promising for reducing the allergenic potential of apples.

Maize IgE binding proteins: each plant a different profile?

Background

Allergies are nearly always triggered by protein molecules and the majority of individuals with documented immunologic reactions to foods exhibit IgE hypersensitivity reactions. In this study we aimed to understand if natural differences, at proteomic level, between maize populations, may induce different IgE binding proteins profiles among maize-allergic individuals. We also intended to deepen our knowledge on maize IgE binding proteins.

Results

In order to accomplish this goal we have used proteomic tools (SDS-PAGE and 2-D gel electrophoresis followed by western blot) and tested plasma IgE reactivity from four maize-allergic individuals against four different protein fractions (albumins, globulins, glutelins and prolamins) of three different maize cultivars. We have observed that maize cultivars have different proteomes that result in different IgE binding proteins profiles when tested against plasma from maize-allergic individuals. We could identify 19 different maize IgE binding proteins, 11 of which were unknown to date. Moreover, we found that most (89.5%) of the 19 identified potential maize allergens could be related to plant stress.

Conclusions

These results lead us to conclude that, within each species, plant allergenic potential varies with genotype. Moreover, considering the stress-related IgE binding proteins identified, we hypothesise that the environment, particularly stress conditions, may alter IgE binding protein profiles of plant components.

Identification and quantification of tomato allergens: in vitro characterization of six different varieties

BACKGROUND

The prevalence of sensitization to tomato has been estimated in 6.5% in a Mediterranean population.

OBJECTIVES

To characterize the allergenic profile of 6 commonly ingested varieties of tomato and to identify and quantify the most representative allergens.

METHODS

Rama, Rambo, Canario, Kumato, Pera and Raf tomato varieties were carefully peeled and extracts from peel and pulp prepared. The extracts were characterized by SDS-PAGE and immunoblot. Lyc e 3 and osmotin-like protein (OLP) were identified by LC MS/MS and PG2A by immunoblot with a specific polyclonal antibody. Protein content and allergen concentration (Lyc e 3 and PG2A) were measured by scanning densitometry after identification. One hundred and ninety-one patients were enrolled in the study. Specific IgE to all tomato extracts was evaluated by direct ELISA.

RESULTS

Eighty (41.7%) individuals reported symptoms after contact/ingestion with tomato, most of them oral symptoms. Protein profile and allergen quantification of the 6 varieties showed differences in the allergen composition. Lyc e 3 was visualized in all extracts, being the most abundant in all cases. PG2A and OLP were identified in all peel extracts and in some pulp extracts. Higher specific IgE values were obtained for the Kumato variety. Immunoblot showed the existence of several bands with IgE-binding capacity, especially at 12 and 45-50 kDa.

CONCLUSIONS

The study demonstrates differences in the antigenic and allergenic profiles of the analyzed varieties and variations in their allergenic composition, affecting the diagnostic capacity. LTP and PG2A are important tomato allergens in our population but other IgE-binding capacity proteins are also involved.

Measurement of lipid transfer protein in 88 apple cultivars

BACKGROUND

Fruits are a major cause of food allergy in adults. Lipid transfer proteins (LTP) are implicated in severe allergic reactions to fruits, but little is known about LTP content in different cultivars.

OBJECTIVE

Determination of the levels of LTP in a wide range of apple cultivars.

METHODS

LTP was measured in apples from 53 cultivars grown in Italy and 35 grown in The Netherlands, using three different immunoassays: a competitive ELISA (cELISA), a sandwich ELISA (sELISA) and a RAST inhibition (RI). Selected cultivars were evaluated using the basophil histamine release test (BHR), skin prick test (SPT) and double-blind, placebo-controlled food challenge (DBPCFC).

RESULTS

LTP levels measured with the three immunoassays were significantly correlated, as judged by Pearson's correlation (0.61 < Rp < 0.65; p < 0.0001), but differed with respect to the actual quantities: 3.4-253.2 (sELISA), 2.7-120.2 (cELISA) and 0.4-47.3 microg/g tissue (RI). Between cultivars, LTP titers varied over about a two-log range. Pilot in vitro and in vivo biological testing (BHR, SPT and DBPCFC) with selected cultivars supported the observed differences in LTP levels.

CONCLUSIONS

Around 100-fold differences in LTP levels exist between apple cultivars. Whether the lowest observed levels of LTP warrant designation as hypo-allergenic requires more extensive confirmation by oral challenges. Determination of cultivar variation in LTP levels provides important information for growers and consumers. Comparison to earlier reported Mal d 1 levels in the same cultivars reveals that a designation as low allergenic does not always coincide for both allergens.

Assessing allergen levels in peach and nectarine cultivars

BACKGROUND

The lipid transfer protein Pru p 3 has been identified as a major peach fruit allergen. However, the putative peach member of the Bet v 1 family, Pru p 1, has been neither identified nor characterized.

OBJECTIVES

To determine the distribution and solubility properties of the main peach allergens and to quantify Pru p 3 and Pru p 1 levels in peach and nectarine cultivars.

METHODS

Peach peel and pulp were extracted using different buffers, and extracts were analyzed by means of sodium dodecyl sulfate-polyacrylamide gel electrophoresis and immunodetection using polyclonal antibodies against lipid transfer proteins, profilins, and Bet v 1 homologues. Pru p 3 was quantified in peach and nectarine cultivars using a sandwich enzyme-linked immunosorbent assay method. A similar method was developed to quantify Pru p 1.

RESULTS

A differential distribution between peel and pulp and different solubility properties were found for Pru p 3, Pru p 1, and peach profilin. Mean Pru p 3 levels were 132.86, 0.61, and 16.92 microg/g of fresh weight of peels, pulps, and whole fruits, respectively. The corresponding mean Pru p 1 levels were 0.62, 0.26, and 0.09 microg/g of fresh weight. Most US cultivars showed higher levels of both allergens than Spanish cultivars.

CONCLUSIONS

The different distribution and solubility properties of the main peach allergens can determine the quality of fruit extracts used as diagnostic tools. These differences, together with the natural variation of Pru p 3 and Pru p 1 levels among peach and nectarine cultivars, can be exploited to reduce peach allergenicity by means of industrial processing and plant breeding.

Lipid transfer protein allergy: primary food allergy or pollen/food syndrome in some cases

PURPOSE OF REVIEW

To summarize recent findings on non-specific lipid transfer proteins in food allergy, with a specific focus on the localization, stability and route of sensitization.

RECENT FINDINGS

Plant non-specific lipid transfer proteins are major food allergens, especially in the Mediterranean area. They have been identified as allergens in a number of foods and the list grows ever longer. As non-specific lipid transfer proteins are considered to be "true" food allergens that sensitize directly via the gastrointestinal tract their stability during food processing and gastric digestion has been studied in more detail. In addition, several groups have tried to determine the sensitization patterns of lipid transfer protein-reactive patients, to determine and possibly clarify the observed geographical differences in sensitization. Different sensitization routes (via the respiratory tract or even transdermally) have been suggested.

SUMMARY

As the structure and molecular properties of non-specific lipid transfer proteins are resolved and more purified non-specific lipid transfer proteins become available for diagnostic purposes, detailed studies on the sensitization pattern and route are becoming feasible. Continuing studies on the pattern of lipid transfer protein sensitization will give more insight into the development and possible treatment of lipid transfer protein-related food allergy.