Abstract
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.
Keywords: allergy, antioxidants, apple varieties, birch pollinosis, polyphenols
Abbreviations
- BAT
basophil activation test
- BMI
body mass index
- CCDs
cross reactive carbohydrate determinants
- EAST
Enzyme Allergosorbent Test
- ELISA
Enzyme‐Linked Immunosorbent Assay
- EST
expressed sequence tag
- HR
histamine release test
- LG
linkage group
- (ns)LTPs
(non‐specific) lipid transfer proteins family
- OAS
oral allergy syndrome
- OPT
oral provocation test
- PPO
polyphenol oxidase enzyme
- PR
Pathogen Resistance Proteins
pathogenesis‐related protein family
- PR
Pathogen Resistance Proteins
pathogenesis‐related protein family
- R
resistant
- RAST
inhibition and immunoblotting
- S
susceptible
- sIgE
specific IgE
- SPT
skin prick test
- VS
very susceptible
1. BACKGROUND
Apple tree fruits (Malus × domestica Borkh.) are a rich source of nutrients and nutraceuticals like polyphenols and other phytochemicals. The main components of apple phytochemicals are phenolic acids, dihydrochalcones, flavonoids (quercetin glycosides), catechins and oligomeric procyanidins as well as cyanidin glucosides in red fruits. 1 Due to the listed ingredients, apple may reduce risk of chronic diseases, through various mechanisms, including antioxidant or anti‐proliferative. 2 They may also improve the functioning of the digestive tract, regulate body mass and increase the respiratory efficiency of the body. 3 Unfortunately, apples could also be the cause of allergies including severe reactions.
About 5%–8% children and 2%–3% adults suffer from food allergy. 4 Allergies to fruits like apple, pear, peach, apricot, cherry, and to vegetables such as carrot, celery and potato are more frequent in older children and adults and they are predominantly associated with cross‐reactivity between aeroallergens like tree pollens, grass or ragweed pollens and food allergens due to structural homology of some allergenic proteins. 5 In North and Central Europe, the most frequent example is the symptomatic response to raw apple in patients sensitised to birch tree pollens. 6 The primary sensitisation to allergenic molecules of Betula verrucosa (e.g., Bet v1) triggers the synthesis of specific IgE antibodies which are capable to cross‐react with its homologues in apple (e.g., Mal d1). The clinical expression of such immune‐mediated reaction includes rapid‐onset pruritus of the oropharynx, angio‐oedema, ears' pruritus and sometimes larynx constriction. These symptoms known as an Oral Allergy Syndrome (OAS) are usually mild and occur directly after exposure to the allergens. The apple allergens are heat‐labile and susceptible to digestion thus the symptoms are rarely connected with gastrointestinal track. Asero et al. 7 estimated the pathogenesis‐related protein family PR‐10 and profilin are although labile molecules, can induce systemic reactions facilitated by proton pump inhibitors, ingestion of large amounts of raw foods and fasting. The cross‐reactivity properties and allergenic potential of different apple cultivars may vary and this phenomenon may be clinically useful in planning oral immunotherapy treatment with the use of less allergenic cultivars. These issues will be discussed in our article.
1.1. Sensitising components
1.1.1. Mal d proteins
So far, four allergens have been identified and officially incorporated into the nomenclature by WHO/IUIS 8 in apples (Malus × domestica Borkh.): Mal d 1, Mal d 2, Mal d 3 and Mal d 4. Among them, Mal d 1 is clinically the most important allergen in North and Central Europe, Mal d 3 in Southern Europe. In Mediterranean, the two other proteins Mal d 2 and Mal d 4, are also associated with the hyper‐reactivity to apple fruits.
Mal d 1 is identified as a 17‐18 kDa protein of 158‐159 amino acids encoded by 480‐483 nucleotides. 9 Its biological function is connected with fungal and bacterial infection response due to the ribonuclease activity of proteins belonging to the pathogenesis‐related protein family (PR‐10). Mal d 1 may also be involved in binding and transport of plant steroids and intracellular signalling. 10 , 11 , 12 The abiotic and biotic stress affects the content of Mal d 1 allergen. Time and conditions of apple fruits storage may quantitatively alter the allergenic properties of their proteins. 13 Moreover, patients with birch pollen‐related food allergies report the severity of their symptoms strongly dependent on apple variety and the degree of maturity. 14 Variability in the allergenic potency might result from the different expression levels of the Mal d 1 isoforms clustered in four groups (Mal 1.01–Mal d 1.04) (www.allergen.org). In the apple genome, many sequences of isoallergens has been identified so far. Mal d 1 is encoded by 18 genes, seven of these are clustered into linkage group 13 (LG13), nine genes clustered into LG16 and one of them is unclustered. 9 The gene family was divided into five groups depending on number and size of introns and analysis of EST (expressed sequence tag). 15 In the first subfamily of the Mal d 1 protein, two major genetic variants Mal d 1.01 and Mal d 1.02, in the second Mal d 1.04 and Mal d 1.05, in the third Mal d 1.06A, Mal d 1.06B, Mal d 1.06C, in the fourth: Mal d 1.07‐1.09, Mal d 1.03A‐G and in the fifth Mal d 1ps1 have been identified. 9 Gao et al. 16 demonstrated the association of expression of Mal d 1.04 and Mal d 1.06A with the allergenicity. Moreover, Mal d 1.06A showed the allele dosage effect on the amount of Mal d 1 protein. 16
Another apple allergen Mal d2 (23 kDa), is also known to be connected with apple allergenicity phenomenon. Mal d 2 belongs to thaumatin‐like proteins (TLPs) group with antifungal properties (PR‐5). 17 TLPs are major protein component in mature apple fruit 18 and they are considered as a panallergen in food and in pollen. 19 Mal d 2 is similar to protein extracted from the fruit Thaumatococcus daniellii. Mal d 2 proteins are encoded by Mal d 2.01, 2.02 and 2.03 genes, 20 although there is only one isoform (Mal d 2.01) officially recognised by WHO/IUIS. 8 Two copies of the Mal d 2.01 gene are slightly different in the signal peptide and intron size mapped at the same position on LG 9. 21 Mal d 2 proteins are very stable molecules, resistant to heat denaturation and proteolysis, as a result of the presence of the eight disulphide bridges which hold together three‐dimensional structure. 22 Hsieh et al. 23 identified Mal d 2 as an in vitro reactive allergen among 75% (25/34) of apple allergic subjects recruited in the study in USA. 23
A 9 kDa molecular weight protein—Mal d 3 identified in apples, belongs to the non‐specific lipid transfer proteins family (nsLTPs). Proteins from that family are major allergens sensitising patients with non‐pollen related allergies to Rosaceae fruits. 24 , 25 , 26 , 27 In Mediterranean countries, patients allergic to apples, but not sensitised to Betula pollen, confer allergies to peach and other Rosaceae and non‐Rosaceae fruits. Apple Mal d 3 allergens cross‐react with peach Pru p 3 allergens. Mal d 3 is encoded by two genes Mal d 3.01 and Mal d 3.02. 25
Mal d 4 is a cytosolic protein 12–15 kDa, 24 playing essential role in plant growth and development by participating in the regulation of actin filament polymerisation. 20 Allergy to Mal d 4 occurs mostly in the Mediterranean, with minor role in apple sensitisation. 26 This allergen is involved in sensitisation to fruits of other species and strongly cross‐reacts with birch pollen Bet v 2 profilin. 13 , 28 Mal d 4 is encoded by three genes Mal d 4.01, Mal d 4.02 and Mal d 4.03, 20 among them Mal d 4.02 has the highest expression level. 21
1.2. CCDs—cross reactive carbohydrate determinants
About 20% of sensitised patients to pollen produce IgE antibodies that can bind carbohydrate determinants. IgE specific to CCDs are considered to have no or minor clinical significance, Glycans with carbohydrate determinants in plants and in invertebrates differ from those glycoproteins existing in mammals. These foreign epitopes for humans are highly immunogenic resulting in specific IgE antibodies. 29 The widespread presence of fucose and xylose on N‐linked glycans of plants and in invertebrates may explain the high degree of cross‐reactivity that has been reported for CCD‐specific IgE antibodies. 30 The clinical relevance of IgE antibodies to CCDs relies on the composition of the allergen‐monovalent or multivalent with respect to the carbohydrate determinant.
To avoid misdiagnosis, an investigation of the presence of CCD antibodies should be conduct. Determination of anti‐CCD IgE antibody in blood can be tested with bromelain or horseradish peroxidase, and also by the use of a test specific to MUXF3, a common plant glycan structure. 31 A positive in vitro test and a negative skin prick test to the same plant food allergen may indicate presence of non‐cross‐linking CCD‐specific IgE antibodies to that allergen. However, this phenomenon does not exclude cross‐linking to other allergens with multivalent CCD epitopes or the presence of concomitant IgE antibodies to peptide epitopes. 32
1.3. Allergenicity varies regards to apple tree varieties and cultivation method
Despite common allergies to apples, only a few studies assessing the amount of different apple allergens were conducted in commonly cultivated varieties: Golden Delicious, Granny Smith, Fuji, Santana, Cox's Orange Pippin, Topaz, Braeburn 12 , 30 , 31 and mainly in relation to the Mal d 1 (Tables 1 and 2). The extensive use of these popular cultivars has resulted in uniformity of commercial apple orchards and the limitation of genetic biodiversity. 33
TABLE 1.
The list of apple cultivars and methods used for Mal d allergens studies
| Cultivar | Analysis method | Mal d 1 | Mal d 2 | Mal d 3 | Mal d 4 |
|---|---|---|---|---|---|
| Golden Delicious | Gene expression | 3, 21, 34, 35, 36 | 21, 34, 35, 36 | 21, 35, 36, 37 | 21, 38 |
| ELISA, EAST, immunoblotting | 3, 14, 16, 21, 34, 36, 38, 39, 40, 41, 42, 48, 49, 50 | 21, 34 | 21, 42, 43 | 21, 38 | |
| SPT/prick‐to‐prick | 36, 41, 44 | 36 | 43 | 21, 35 | |
| Granny Smith | Gene expression | 3, 21, 36 | 21 | 21 | 21 |
| ELISA, EAST, immunoblotting | 3, 14, 16, 31, 34, 42, 48, 50 | 36 | 43 | ||
| SPT/prick‐to‐prick | 44 | 43 | |||
| Baeburn | Gene expression | 21 | 21 | 21 | 21 |
| ELISA, EAST, immunoblotting | 13, 14, 21, 35, 38, 39, 40 | 21 | 21 | 21 | |
| SPT/prick‐to‐prick | 13 | ||||
| Elstar | Gene expression | 3 | |||
| ELISA, EAST, immunoblotting | 3 | 38 | |||
| SPT/prick‐to‐prick | 38 | ||||
| Topaz | Gene expression | ||||
| ELISA, EAST, immunoblotting | 13, 39, 40, 45 | ||||
| SPT/prick‐to‐prick | |||||
| Elise | Gene expression | ||||
| ELISA, EAST, immunoblotting | 13, 45 | ||||
| SPT/prick‐to‐prick | 44 | ||||
| Santana | Gene expression | 46 | |||
| ELISA, EAST, immunoblotting | 49 | ||||
| SPT/prick‐to‐prick | 16, 44 | ||||
| Cox's Orange Pippin, Jonagored, Jonagold, Boskoop, Priscilla, Fuji, Jonathan, prima, Fiesta, Mcintosh, Gala, Idared, Gloster, Szampion | Gene expression | 3, 36, 47 | |||
| ELISA, EAST, immunoblotting | 3, 14, 28, 36, 38, 40, 45, 47, 50 | 43 | |||
| SPT/prick‐to‐prick | 16, 41, 44 | 43 | |||
| Old varieties: Pink Lady Cripps Pink, Annurca, ‘Calvilla Bianca d’Inverno, Mutsu, Osnabruecker Renette, Delorina, Resista, Rajca, Grey Renette, Starking | Gene expression, | 21, 36 | 21, 36 | 21, 36 | 21 |
| ELISA, EAST, immunoblotting | 21, 36 | 21, 36 | 43 | 21 | |
| SPT/prick‐to‐prick | 40,41,44 | 43 | 43 |
Abbreviations: EAST, Enzyme Allergosorbent Test; ELISA, enzyme‐linked immunosorbent assay; SPT, Skin Prick Test.
TABLE 2.
Mal d 1 protein content across apple cultivars
| Cultivar | Mal d 1 content | Units | Literature |
|---|---|---|---|
| Golden Delicious | 12.1 | µg/g FW | 3 |
| C50 = 0.12, C50 = 0.36 | µg | 14 | |
| 45 (4.5) | µg/g (mg/100 g) | 48 | |
| 2.9, 3.4, about 10.0 | µg/g FW | 49 | |
| 14.1–135.17 | µg/g | 38 | |
| 7.3–18.6 | µg/g FW | 16 | |
| 6.2–7.6 | µg/g f FW | 40 | |
| 7–8 (0.7–0.8) | µg/g (mg/100 g) | 34 | |
| 7.6–17 | µg/g | 39 | |
| 5.5–12.8 | µg/g | 50 | |
| Granny Smith | 5.95–18.17 | µg/g | 16 |
| 12.14, 8.81 | µg/g FW | 3 | |
| 16 (1.6) | µg/g (mg/100 g) | 48 | |
| 2.3–6.4 | µg/g FW | 34 | |
| 5.45–12.14 | µg/g | 50 | |
| Baeburn | 9.45–271.20 | µg/g | 38 |
| C50 = 0.12 | µg | 14 | |
| Topaz | 2.0–6.4 | µg/g FW | 40 |
| 6.3–16.1 | µg/g | 39 | |
| <1–25 | µg/g FW | 45 | |
| Santana | 0.5, 2.3, about 5.0 | µg/g FW | 49 |
| Elise | 0.25–17 | µg/g FW | 45 |
| Fuji | 11.50 | µg/g FW | 3 |
| 5.4, 11.5 | µg/g | 28 | |
| 32.84–455.01 | µg/g | 38 | |
| 50.8 | µg/g | 47 | |
| Boskoop | C50 = 2 | µg | 14 |
| 1–25 | µg/g FW | 45 | |
| Jonagold | 7 (0.7) | µg/g (mg/100 g) | 48 |
| 3.33–5.5 | µg/g FW | 50 | |
| 1.3–8.7 | µg/g FW | 40 | |
| 12.98–38.82 | µg/g | 38 | |
| 17.2 | µg/g | 47 | |
| Idared | 8 (0.8) | µg/g (mg/100 g) | 48 |
| Gloster | 4 (0.4) | µg/g (mg/100 g) | 48 |
| Gala | 14.6 | µg/g FW | 40 |
Abbreviations: C50, concentration of protein causing 50% inhibition of IgE binding from patients sera; FW, fresh weight.
The issue of the expression of genes encoding allergens in apples is also poorly understood. Even limited number of publications regarding the gene expression encoding apple allergens showed an association among gene expression and degree of maturity, storage conditions mainly with respect to the Mal d 1 gene (Table 1). Therefore, it is expected to expand similar research to a larger number of varieties, in particular with regard to old ones. There are only a few papers 40 , 44 describing allergen gene expression in old varieties, which are valuable in terms of taste, nutritional value, processing or for breeding. Nevertheless, cultivation of apple varieties with low allergenic potential is not developed. Currently, only Santana, Topaz and Elise cultivars, are considered hypoallergenic, and are quite well tolerated by patients with allergies. It has been shown that the Santana variety is characterised by considerable resistance to apple scab, thanks to which it is possible to significantly reduce the use of fungicides in its cultivation. 51 There is some evidence that pesticide treatment may lead to an even more robust response inducing higher expression of Mal d 1 than biotic factor. 40
1.4. Abiotic factors influencing allergenicity
Variation of Mal d 1 content during ripening, postharvest maturity, and storage time and conditions were confirmed only in the context of Golden Delicious, Topaz, Braeburn and Cox’Orange Pippin apple varieties. During the ripening period, content of Mal d 1 allergens continuously increases from about 0.2 mg/100 g fresh weight to approximately 0.8 mg/100 g fresh weight (130–164 days after blooming respectively). Mal d 1 content in apple fruit varieties Braeburn, Topaz harvested at different stages of ripeness revealed no differences. 36 After an additional shelf life, significantly higher Mal d 1 concentration in the overripe fruit in comparison to the unripe fruit were determined. Storage, at ambient temperature, of 12 weeks cold‐stored fruit of above mentioned cultivars led also to Mal d 1 accumulation in unripe and overripe harvested fruit, contrary to ripe fruit, where Mal d 1 remained stable. 39 The study emphasises the need for further research on other apple cultivars to ascertain the differences of Mal d 1 content at different maturity stage and during apple storage. Several studies shown the elevation of Mal d 1 protein content and up‐regulation of Mal d 1 gene expression during storage and by cold stress. 40 However, Botton et al. 21 indicated stable level of gene expression in analysed apple cultivars, inter alia in Golden Delicious and Braeburn. Mal d 3 expression was two to five times higher in apple skin than in a pulp and down‐regulated upon storage time by about 5 months. The duration of storage time down regulates Mal d 4 coding genes. 21 Yang et al. 35 showed a decrease in expression of the Mal d 4 isoforms after harvest and during ripening. It is suggested that different responses to ethylene can affect profilin gene expression.
A point of interest is that organic farming weakened Mal d content, 52 unfortunately, commercial varieties with a significantly reduced resistance to apple diseases are not suitable for this type of crop. We should focus our attention on old varieties, in which a significant resistance to fungal diseases is observed, making them suitable for organic farming that is getting modern nowadays. Moreover, the impact of cultivation methods on allergenicity is not established nor in commonly cultivated apple trees neither in old cultivars.
1.5. Biotic factors
Plants react to pathogen attacks (Table 3), wounding, UV‐B radiation, osmotic shock, low temperature, water deficit, chemicals like ethylene or salicylic acid, inter alia by producing proteins belonging to the PR (Pathogen Resistance Proteins) family. Three of the four main apple allergens belongs to PR, which are connected with natural resistance to powdery mildew or/and to apple scab or to other stressors and chemicals. 53
TABLE 3.
Fungi disease susceptibility and allergenicity
| Apple variety | Apple scab | Powdery mildew | Allergenicity | Study |
|---|---|---|---|---|
| Golden delicious | S | VS | High | 54 |
| Granny smith | S | VS | Low | 55 |
| Braeburn | R | R | Low/high | 14,55 |
| Elstar | S | S | Low | 55 |
| Topaz | R | R | Low | 55 |
| Elise | S/R | S | Low | 55 |
| Santana | R | S | Low | 55 |
Abbreviations: R, resistant; S, susceptible; VS, very susceptible.
1.6. Allergenicity modifying factors
The allergenicity of apples is more complex due to the interactions of Mal d 1 protein with polyphenols (catechin) and enzymatic antioxidant system. The reaction between Mal d 1 and oxidised polyphenols can result in decrease of IgE binding as shown in Braeburn cultivar. 39 On the other hand, in Topaz, with high polyphenols content and low activity of PPO (polyphenol oxidase enzyme) conferring a high total anti‐oxidative capacity, IgE binding to Mal d 1 is also reduced. 56 According to Schmits‐Eiberger and Matthes, 39 in the cv. Braeburn, cv. Golden Delicious and cv. Topaz amount of total polyphenols were stable during maturation; however during storage, polyphenol content significantly decreased.
Traditional cultivation of apple varieties with low allergenic potentials is not well developed. Currently, Santana, Topaz and Elise cultivars, are considered as hypoallergenic, and are quite well tolerated in patients experiencing OAS syndrome. 40 Furthermore, it has been demonstrated that Santana is characterised by considerable resistance to apple scab, thanks to which it is possible to significantly reduce the usage of chemicals with anti‐fungal properties in its cultivation, 51 thus the use of organic cultivation of this variety may led to reduce the amount of allergenic proteins. In a recent study of allergenic potential of apples cultivars, tested by prick‐to‐prick skin tests and provocation test in 52 patients with birch pollen hay fever and OAS, significant differences among various cultivars were revealed. Red‐fleshed cultivars gave the mildest reactions, being proposed as potentially useful tool in oral immunotherapy treatment in patients with birch pollen allergy and OAS due to birch‐apple cross‐reactivity. 57 Post‐harvest treatment may have additional role in apple fruit allergenicity. Hsieh et al. 23 revealed that prolonged storage at 4°C of Golden Delicious and Granny Smiths fruits can elevate Mal d 1 and Mal d 2 protein levels. In low allergenic cultivars like Santana and Elise, Mal d 1 proteins increased along with storage time, but after treatment with MCP‐1‐inhibiting ripening, the content of Mal d 1 protein was reduced. 45
2. CONCLUSIONS
In Northern and Central Europe, apple allergies are mostly related to birch pollen sensitisation and are caused by cross‐reactive proteins Bet v 1 and Mal d 1. In the Mediterranean, apple allergies are less frequent but severe and associated with sensitisation to LTPs (Mal d 3).
Variation in the Mal d 1 isoforms expression may account for the variability of allergenic potency of apple cultivars, which suggests that genetic factors could have a major role in controlling the Mal d 1 allergenicity in mature apples.
The differences in the allergenic potential of apple fruits can be also the effect of the degree of ripeness of the fruit, as a result of an accumulation of Mal d 1 protein during maturation. Similarly, the time and conditions of fruit storage affect the accumulation of the Mal d 1 and Mal d 2 allergens as shown in Golden Delicious and Granny Smiths varieties.
The total anti‐oxidative status of apple fruits and interactions of polyphenols with Mal d 1 protein can affect the allergenic potential and the ability to bind IgE antibodies.
Currently, only the Topaz, Elise and Santana varieties are considered to be well tolerated by apple allergic patients.
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. Knowledge of the molecular mechanism of apples allergenicity and factors that modify the reaction severity could facilitate medical counselling and improve patients' care with allergies related with apple fruits.
CONFLICT OF INTERESTS
The authors declare that there are no conflict of interests.
AUTHOR CONTRIBUTIONS
Aleksandra Siekierzynska made substantial contributions to conception and design and drafted the manuscript. Aleksandra Siekierzynska, Aleksander Myszka and Marta Burzynska participated in literature study. Dorota Piasecka‐Kwiatkowska, Barbara Sozanska and Tomasz Sozanski revised critically for important intellectual content.
ACKNOWLEDGEMENTS
This study was co‐financed within the framework of the Polish Ministry of Science and Higher Education's program: ‘Regional Initiative Excellence’ in the years 2019–2022 (no. 005/RID/2018/19), financing amount 12,000,000 PLN.
REFERENCES
- 1. Kalinowska M, Bielawska A, Lewandowska‐Siwkiewicz H, Priebe W, Lewandowski W. Apples: content of phenolic compounds vs. variety, part of apple and cultivation model, extraction of phenolic compounds, biological properties. Plant Physiol Biochem. 2014;84:169‐188. https://linkinghub.elsevier.com/retrieve/pii/S0981942814002873 [DOI] [PubMed] [Google Scholar]
- 2. Breinholt V. Desirable versus harmful levels of intake of flavonoids and phenolic acids. In Natural Antioxidants and Anticarcinogens in Nutrition, Health and Disease. Elsevier; 1999. [Google Scholar]
- 3. Marzban G, Puehringer H, Dey R, et al. Localisation and distribution of the major allergens in apple fruits. Plant Sci. 2005;169(2):387–394. [Google Scholar]
- 4. Hassan AKG, Venkatesh YP. An overview of fruit allergy and the causative allergens. Eur Ann Allergy Clin Immunol. 2015;47(6):180–187. [PubMed] [Google Scholar]
- 5. Popescu F‐D. Cross‐reactivity between aeroallergens and food allergens. World J Methodol. 2015;5(2):31–50. [DOI] [PMC free article] [PubMed] [Google Scholar]
- 6. Fernández‐Rivas M, Bolhaar S, González‐Mancebo E, et al. Apple allergy across Europe: how allergen sensitization profiles determine the clinical expression of allergies to plant foods. J Allergy Clin Immunol. 2006;118(2):481–488. [DOI] [PubMed] [Google Scholar]
- 7. Asero R, Ariano R, Aruanno A, et al. Systemic allergic reactions induced by labile plant‐food allergens: seeking potential cofactors. A multicenter study. Allergy Eur J Allergy Clin Immunol. 2020;1–7. [DOI] [PubMed] [Google Scholar]
- 8. WHO/IUIS . Allergen Nomenclature Home Page . http://www.allergen.org/. Accessed July 8, 2020.
- 9. Gao ZS, Van De Weg WE, Schaart JG, et al. Genomic cloning and linkage mapping of the Mal d 1 (PR‐10) gene family in apple (Malus domestica). Theor Appl Genet. 2005;111:171–183. [DOI] [PubMed] [Google Scholar]
- 10. Markovic‐Housley Z, Degano M, Lamba D, et al. Crystal structure of a hypoallergenic isoform of the major birch pollen allergen Bet v 1 and its biological function. J Allergy Clin Immunol. 2002;325(1):123–133. [DOI] [PubMed] [Google Scholar]
- 11. Neudecker P, Schweimer K, Nerkamp J, et al. Allergic cross‐reactivity made visible. Solution structure of the major cherry allergen Pru av 1. J Biol Chem. 2001;276(25):22756–22763. [DOI] [PubMed] [Google Scholar]
- 12. Pühringer H, Moll D, Hoffmann‐Sommergruber K, Watillon B, Katinger H, Da Machado Câmara ML. The promoter of an apple Ypr10 gene, encoding the major allergen Mal d 1, is stress‐ and pathogen‐inducible. Plant Sci 2000;152(1):35–50. [Google Scholar]
- 13. Bolhaar STHP, Van De Weg WE, Van Ree R, et al. In vivo assessment with prick‐to‐prick testing and double‐blind, placebo‐controlled food challenge of allergenicity of apple cultivars. J Allergy Clin Immunol. 2005;116(5):1080–1086. [DOI] [PubMed] [Google Scholar]
- 14. Vieths S, Jankiewicz A, Schöning B, Aulepp H. Apple allergy: The IgE‐binding potency of apple strains is related to the occurrence of the 18‐kDa allergen. Allergy. 1994;49(4):262–271. [DOI] [PubMed] [Google Scholar]
- 15. Pagliarani G, Paris R, Arens P, et al. A qRT‐PCR assay for the expression of all Mal d 1 isoallergen genes. BMC Plant Biol. 2013;13(1):1–13. [DOI] [PMC free article] [PubMed] [Google Scholar]
- 16. Gao Z, Weg EWVDe, Matos CI, et al. Assessment of allelic diversity in intron‐containing Mal d 1 genes and their association to apple allergenicity. BMC Plant Biol. 2008;116. [DOI] [PMC free article] [PubMed] [Google Scholar]
- 17. Krebitz M, Wagner B, Ferreira F, et al. Plant‐based heterologous expression of Mal d 2, a thaumatin‐like protein and allergen of apple (Malus domestica), and its characterization as an antifungal protein. J Mol Biol. 2003;329(4):721–730. [DOI] [PubMed] [Google Scholar]
- 18. Oh DH, Song KJ, Shin YU, Chung WIl. Isolation of a cDNA encoding a 31‐kDa, pathogenesis‐related 5/thaumatin‐like (PR5/TL) protein abundantly expressed in apple fruit (Malus domestica cv. Fuji). Biosci Biotechnol Biochem. 2000;64:355–362. [DOI] [PubMed] [Google Scholar]
- 19. Breiteneder H, Radauer C. A classification of plant food allergens. J Allergy Clin Immunol. 2004;58:1093–1100. [DOI] [PubMed] [Google Scholar]
- 20. Gao ZS, Van De Weg WE, Schaart JG, et al. Genomic characterization and linkage mapping of the apple allergen genes Mal d 2 (thaumatin‐like protein) and Mal d 4 (profilin). Theor Appl Genet. 2005;111:1087–1097. [DOI] [PubMed] [Google Scholar]
- 21. Botton A, Lezzer P, Dorigoni A, Barcaccia G, Ruperti B, Ramina A. Genetic and environmental factors affecting allergen‐related gene expression in apple fruit (Malus domestica L. Borkh). J Agric Food Chem. 2008;56(15):6707–6716. [DOI] [PubMed] [Google Scholar]
- 22. Smole U, Bublin M, Radauer C, Ebner C, Breiteneder H. Mal d 2, the thaumatin‐like allergen from apple, is highly resistant to gastrointestinal digestion and thermal processing. Int Arch Allergy Immunol. 2008;147(4):289–298. [DOI] [PubMed] [Google Scholar]
- 23. Hsieh LS, Moos M, Lin Y. Characterization of apple 18 and 31 kD allergens by microsequencing and evaluation of their content during storage and ripening. J Allergy Clin Immunol. 1995;96(6):960–970. [DOI] [PubMed] [Google Scholar]
- 24. Poltronieri P, Hong Y. Applied plant genomics and biotechnology. Appl Plant Genomics Biotechnol. 1. Woodhead Publishing; 2015; 1–356. [Google Scholar]
- 25. Gao ZS, Van De Weg WE, Schaart JG, et al. Linkage map positions and allelic diversity of two Mal d 3 (non‐specific lipid transfer protein) genes in the cultivated apple (Malus domestica). Theor Appl Genet. 2005;110:479–491. [DOI] [PubMed] [Google Scholar]
- 26. Andersen MBS, Hall S, Dragsted LO. Identification of European allergy patterns to the allergen families PR‐10, LTP, and profilin from Rosaceae fruits. Clin Rev Allergy Immunol. 2011;41:1–3. [DOI] [PubMed] [Google Scholar]
- 27. Gomez F, Aranda A, Campo P, et al. High prevalence of lipid transfer protein sensitization in apple allergic patients with systemic symptoms. PLoS One. 2014;9(9):e107304. [DOI] [PMC free article] [PubMed] [Google Scholar]
- 28. Asero R, Mistrello G, Roncarolo D, Amato S, Falagiani P. Analysis of the heat stability of lipid transfer protein from apple [2]. J Allergy Clin Immunol. 2003;112(5):1009–1011. [DOI] [PubMed] [Google Scholar]
- 29. Jin C, Hantusch B, Hemmer W, Stadlmann J, Altmann F. Affinity of IgE and IgG against cross‐reactive carbohydrate determinants on plant and insect glycoproteins. J Allergy Clin Immunol. 2008;121(1):185–190.e2. [DOI] [PubMed] [Google Scholar]
- 30. Homann A, Schramm G, Jappe U. Glycans and glycan‐specific IgE in clinical and molecular allergology: sensitization, diagnostics, and clinical symptoms. J Allergy Clin Immunol. 2017;140(2):356–368. [DOI] [PubMed] [Google Scholar]
- 31. Hemmer W, Wohrl S, Wantke F, Altmann F. Immunocap cellulose displays cross‐reactive carbohydrate epitopes and can cause false‐positive test results in patients with anti‐CCD IgE antibodies. J Allergy Clin Immunol. 2014;141(1):372–381.e3. [DOI] [PubMed] [Google Scholar]
- 32. Van Der Veen MJ, Van Ree R, Aalberse RC, et al. Poor biologic activity of cross‐reactive IgE directed to carbohydrate determinants of glycoproteins. J Allergy Clin Immunol. 1997;100(3):327–334. [DOI] [PubMed] [Google Scholar]
- 33. Cerutti AK, Bruun S, Donno D, Beccaro GL, Bounous G. Environmental sustainability of traditional foods: the case of ancient apple cultivars in Northern Italy assessed by multifunctional LCA. J Clean Prod. 2013;52(1):245–252. [Google Scholar]
- 34. Szamos J, Takács K, Szabó EE, Kovács E, Gelencsér E. Purification of natural Mal d 1 and Mal d 2 allergens and monitoring of their expression levels during ripening in Golden Delicious apple. Food Res Int. 2011;44(9):2674–2678. [Google Scholar]
- 35. Yang XT, Song J, Campbell‐Palmer L, Walker B, Zhang Z. Allergen related gene expression in apple fruit is differentially controlled by ethylene during ripening. Postharvest Biol Technol. 2012;63(1):40–49. [Google Scholar]
- 36. Vegro M, Eccher G, Populin F, et al. Old apple (Malus domestica L. Borkh) varieties with hypoallergenic properties: an integrated approach for studying apple allergenicity. J Agric Food Chem. 2016;64(48):9224–9236. [DOI] [PubMed] [Google Scholar]
- 37. Zuidmeer L, Van Leeuwen WA, Budde IK, et al. Lipid transfer proteins from fruit: cloning, expression and quantification. Int Arch Allergy Immunol. 2005;137(4):273–281. [DOI] [PubMed] [Google Scholar]
- 38. Zuidmeer L, Van Leeuwen WA, Budde IK, et al. Allergenicity assessment of apple cultivars: hurdles in quantifying labile fruit allergens. Int Arch Allergy Immunol. 2006;141(3):230–240. [DOI] [PubMed] [Google Scholar]
- 39. Schmitz‐Eiberger M, Matthes A. Effect of harvest maturity, duration of storage and shelf life of apples on the allergen Mal d 1, polyphenoloxidase activity and polyphenol content. Food Chem 2011;127(4):1459–1464. [Google Scholar]
- 40. Matthes A, Schmitz‐Eiberger M. Apple (Malus domestica L. Borkh.) allergen Mal d 1: effect of cultivar, cultivation system, and storage conditions. J Agric Food Chem. 2009;57(22):10548–10553. [DOI] [PubMed] [Google Scholar]
- 41. Wagner A, Szwed A, Buczyłko K, Wagner W. Allergy to apple cultivars among patients with birch pollinosis and oral allergy syndrome. Ann Allergy Asthma Immunol. 2016;117(4):399–404. [DOI] [PubMed] [Google Scholar]
- 42. Cudowska B, Kaczmarski M, Restani P. Immunoblotting in the diagnosis of cross‐reactivity in children allergic to birch. Rocz Akad Med w Białymstoku. 2005;50:268–273. [PubMed] [Google Scholar]
- 43. Carnés J, Ferrer A, Fernández‐Caldas E. Allergenicity of 10 different apple varieties. Ann Allergy Asthma Immunol. 2006;96(4):564–570. [DOI] [PubMed] [Google Scholar]
- 44. Vlieg‐Boerstra BJ, Van De Weg WE, Van Der Heide S, Dubois AEJ. Where to prick the apple for skin testing? Allergy Eur J Allergy Clin Immunol. 2013;68(9):1196–1198. [DOI] [PubMed] [Google Scholar]
- 45. Kiewning D, Schmitz‐Eiberger M. Effects of long‐term storage on Mal d 1 content of four apple cultivars with initial low Mald1 content. J Sci Food Agric. 2014;94(4):798–802. [DOI] [PubMed] [Google Scholar]
- 46. Kootstra HS, Vlieg‐Boerstra BJ, Dubois AEJ. Assessment of the reduced allergenic properties of the Santana apple. Ann Allergy Asthma Immunol. 2007;99(6):222–225. [DOI] [PubMed] [Google Scholar]
- 47. Sancho AI, Foxalll R, Browne T, et al. Effect of postharvest storage on the expression of the apple allergen Mal d 1. J Agric Food Chem. 2006;54(16):5917–5923. [DOI] [PubMed] [Google Scholar]
- 48. Son DY, Scheurer S, Hoffmann A, Haustein D, Vieths S. Pollen‐related food allergy: cloning and immunological analysis of isoforms and mutants of Mal d 1, the major apple allergen, and Bet v 1, the major birch pollen allergen. Eur J Nutr. 1999;38(4):201–215. [DOI] [PubMed] [Google Scholar]
- 49. Romer E, Chebib S, Bergmann KC, et al. Tiered approach for the identification of Mal d 1 reduced, well tolerated apple genotypes. Sci Rep. 2020;10. [DOI] [PMC free article] [PubMed] [Google Scholar]
- 50. Asero R, Marzban G, Martinelli A, Zaccarini M, Laimer Da Câmara Machado M. Search for low allergenic apple cultivars for birch pollen‐allergic patients: is there a correlation between in vitro a says and patient response? Eur Ann Allergy Clin Immunol. 2006;38(3):94–98. [PubMed] [Google Scholar]
- 51. Schenk MF, Van Der Maas MP, Smulders MJM, et al. Consumer attitudes towards hypoallergenic apples that alleviate mild apple allergy. Food Qual Prefer. 2011;22(1):83–91. [Google Scholar]
- 52. Takács K, Szamos J, Szabó EE, Szabó Z, Nyéki J, Gelencsér É. Apple allergens as affected by cultivation technolog and variental factors. Int J Hortic Sci. 2010;16(3):91–93. [Google Scholar]
- 53. Savazzini F, Ricci G, Tartarini S. Apple allergens genomics and biotechnology: unravelling the determinants of apple allergenicity. Appl Plant Genomics Biotechnol. Elsevier Ltd. 2015;35–54. [Google Scholar]
- 54. Barden JA, Marini RP. Incidence of diseases on fruit of nine apple genotypes as influenced by six fungicide treatments. Fruit Var J. 1998;52(3):136–143. [Google Scholar]
- 55. Vlieg‐Boerstra BJ, Van De Weg WE, Van Der Heide S, et al. Identification of low allergenic apple cultivars using skin prick tests and oral food challenges. Allergy Eur J Allergy Clin Immunol. 2011;66(4):491–498. [DOI] [PubMed] [Google Scholar]
- 56. Matthes A, Schmitz‐Eiberger M. Polyphenol content and antioxidant capacity of apple fruit: effect of cultivar and storage conditions. J Appl Bot Food Qual. 2009;82(2):152–157. [Google Scholar]
- 57. Nothegger B, Reider N, Covaciu CE, et al. Allergen‐specific immunotherapy with apples: selected cultivars could be a promising tool for birch pollen allergy. J Eur Acad Dermatol Venereol. 2020;34(6):1286–1292. [DOI] [PMC free article] [PubMed] [Google Scholar]