Table of Contents

Whole Allergen

g15 Cultivated wheat

g15 Cultivated wheat Scientific Information

Type:

Whole Allergen

Display Name:

Cultivated wheat

Allergen code:

g15

Family:

Poaceae

Species:

Triticum aestivum

Route of Exposure:

Inhalation (1)

Latin Name:

Triticum aestivum

Other Names:

Bread wheat (1)

Summary

Triticum aestivum is a member of the Poaceae family that produces wheat aeroallergens responsible for pollen allergy and occupational respiratory allergy to cereal flour, known as ‘Baker’s asthma’. Sensitization to cultivated wheat causes rhinitis and asthma and is prevalent among patients with respiratory allergies who are multi-sensitized to aeroallergens.

Allergen

Nature

T. aestivum is a self-pollinating (1) cultivated wheat species that is grown in spring and winter for cereal grain (2). It is the main cereal used to produce human and animal food (2).

Cultivated cereals are widely grown throughout the world (3). They mainly flower in spring and produce large amounts of pollen, approximately 40–122 μm in size (1). However, although weather can affect pollen dispersion, the large size of the pollen prohibits dispersion more than 0.5km (1). Exposure to T. aestivum allergens is, thus, generally limited to occupational allergy or to the immediate vicinity of T. aestivum cultivation (1).

Taxonomy

*Taxonomic tree of Triticum aestivum* (3)**
Domain	Eukaryota
Kingdom	Plantae
Phylum	Spermatophyta
Subphylum	Angiospermae
Class	Monocotyledonae
Order	Cyperales
Family	Poaceae
Genus	Triticum

Tissue

Pollen and cereal flour (1).

Epidemiology

Worldwide distribution

Sensitization to cultivated wheat is common in people with respiratory allergies who are multi-sensitized to aeroallergens (1). Sensitization is thought to affect males more than females (Moradi et al, 2018) and a wide range of sensitization frequency (17.7–60.8%) has been reported in studies; cross-reactivity with timothy grass may account for the high percentage of sensitization levels seen (1).

Baker's asthma, an occupational respiratory allergy to cereal flour, affects up to 9% of bakers; it is the leading cause of occupational asthma in France, and the second highest in the UK (4). Among bakers with occupational asthma, 47% are sensitized to the T. aestivum allergen 25 (Tri a 25) (5).

Patients with baker's asthma usually ingest wheat products without issue, although in a study of children with grass pollen allergy, up to 65% had false positive results for wheat extract (6).

Risk factors

Living or working close to T. aestivum cultivation (1).

Occupations that involve working with cereal flours, such as bakers, farmers (1), confectioners, flour millers, and food processors (4).

Environmental Characteristics

Worldwide distribution

T. aestivum can be found worldwide (3) and are well adapted to temperate regions (1).

Route of Exposure

Main

Inhalation (1).

Secondary

Contact (6).

Clinical Relevance

Symptoms of cultivated wheat sensitization include rhinitis, conjunctivitis, urticaria, asthma and, rarely, systemic anaphylaxis (4).

Molecular Aspects

Allergenic molecules

A number of wheat allergens have been identified; some are involved in the development of respiratory allergies and others in the development of wheat food allergy (7).

In a study that investigated the IgE reactivity of different wheat recombinant allergens using serum from 22 patients that suffered from wheat respiratory allergy, the results showed that 91% of sera recognized wheat CAP. The six individual wheat recombinant allergens (thioredoxin H, serine proteinase inhibitor, glutathione transferase, profilin, dehydrin and 1-cis-peroxyredoxine) were recognized between 4.5 and 32% of serum samples (7). Profilin is a common cross-reactive allergen that is present in wheat seeds, wheat pollen and other grass pollens including timothy (7). The recombinant versions of the timothy grass allergens Phl p 1 and Phl p 5 were identified as marker allergens specific for grass pollen allergy (7).

This table, adapted from Allergome.org (8), shows allergens identified in wheat pollen.

Allergen	Type	Mass (kDa)
Tri a 1	β-expansin	30
Tri a 2	Pollen allergen II	13.3
Tri a 3	Unknown	13
Tri a 4	Berberine Bridge Enzymes	57.5
Tri a 5	Ribonucleases	24
Tri a 7	Calcium-binding Proteins	n/a
Tri a 12	Profilin	14
Tri a 13	Polygalacturonases	-

Cross-reactivity

Cross-reactivity has been reported between wild grass and cereal pollen; cultivated maize, rice, wheat, rye, barley and oats, can induce symptoms in individuals sensitized to grass pollen (1). Cross-reactivity with common grass species (Anthoxanthum odoratum, Dactylis glomerata, Lolium perenne, Poapratensis and Phleum pratense) has been shown (9).

The Zea mays allergen 25 (Zea m 25) exhibits high IgE cross-reactivity with the T. aestivum allergen 25 (Tri a 25) (Weichel et al, 2006) while rice pollen shows weak cross-reactivity with wheat (1).

Profilin is recognized as a cross-reactive allergen in patients with baker’s asthma, food and pollen allergy (7).

Compiled By

Author: RubyDuke Communications

Reviewer: Dr.Christian Fischer

Last reviewed: June 2022

References

Damialis A, Konstantinou GN. Cereal pollen sensitisation in pollen allergic patients: to treat or not to treat? Eur Ann Allergy Clin Immunol. 2011;43(2):36-44.
Lukow OM, McVetty PBE. GRAIN PRODUCTION AND CONSUMPTION | Cereal Grains in North America. In: Wrigley C, editor. Encyclopedia of Grain Science. Oxford: Elsevier; 2004. p. 94-106.
CABI. Triticum aestivum (wheat) Wallingford, UK2021 [cited 2022 18.01.22]. Available from: https://www.cabi.org/isc/datasheet/55204.
Ramirez DA, Jr., Bahna SL. Food hypersensitivity by inhalation. Clin Mol Allergy. 2009;7:4.
Weichel M, Glaser AG, Ballmer-Weber BK, Schmid-Grendelmeier P, Crameri R. Wheat and maize thioredoxins: a novel cross-reactive cereal allergen family related to baker's asthma. J Allergy Clin Immunol. 2006;117(3):676-81.
Czaja-Bulsa G, Bulsa M. What Do We Know Now about IgE-Mediated Wheat Allergy in Children? Nutrients. 2017;9(1).
Constantin C, Quirce S, Poorafshar M, Touraev A, Niggemann B, Mari A, et al. Micro-arrayed wheat seed and grass pollen allergens for component-resolved diagnosis. Allergy. 2009;64(7):1030-7.
Allergome.org. Triticum aestivum pollen 2021 [cited 2022 18.01.22]. Available from: http://www.allergome.org/script/search_step2.php.
Hrabina M, Jain K, Gouyon B, editors. Cros“ reactivity between pollen allergens from common Pooideae grasses and cultivated cereals2008.