Table of Contents

Whole Allergen

t206 Chestnut

t206 Chestnut Scientific Information

Type:

Whole Allergen

Display Name:

Chestnut

Allergen code:

t206

Family:

Fagaceae

Species:

C. sativa

Route of Exposure:

Inhalation

Latin Name:

Castanea sativa

Other Names:

Chestnut, Sweet chestnut, European chestnut, Spanish chestnut

Summary

Chestnut trees (Castanea spp.) are distributed across the Northern hemisphere, particularly in Spain and the wider Mediterranean region. Chestnut pollen is produced in large quantities and disperses over long distances. Castanea sativa pollen is a recognized allergen causing rhinoconjunctivitis and asthma. Chestnut pollen is part of the birch-homologous group of allergens, although recent evidence for cross-reactivity with other tree pollens is inconclusive.

Allergen

Nature

Chestnut trees are members of the Fagaceae family, which includes oaks (Quercus spp.) and beeches (Fagus spp.). The sweet chestnut, Castanea sativa var. Miller, is common in deciduous forests throughout Europe, especially in Spain and the wider Mediterranean region (1, 2). Chestnut trees are widely distributed in the Northern hemisphere, from northwest Africa to southwest Asia (2, 3).

Castanea pollen is wind-borne and disperses over long distances due to its small size (2). Pollen production is very high, with 10–12 billion pollen grains per tree released during the pollen season (1). The European chestnut pollen season occurs from June to August, with a peak in late June/early July (4). In South Korea, the chestnut pollen season varies between late April and July according to region (3).

Castanea pollen constitutes 5-7% of annual pollen concentrations in Spain, where high pollen counts correlate with high air temperature (1).

Taxonomy

*Taxonomic tree of Castanea* species (5)**
Domain	Eukaryota
Kingdom	Plantae
Phylum	Spermatophyta
Subphylum	Angioospermae
Class	Dicotyledonae
Family	Fagaceae
Genus	Castanea

Tissue

Tree pollen

Epidemiology

Worldwide distribution

Allergy to chestnut pollen represents a major cause of pollinosis in sub-Mediterranean areas (6).

Environmental Characteristics

Worldwide distribution

Chestnut trees are used in agroforestry, for charcoal production and for ornamental purposes (CABI 2021). In Spain, chestnut trees are economically important as a source of pollen for region-specific honey (1).

Castanea sativa produces edible fruits (chestnuts) which may be consumed whole, or ground to produce chestnut flour used for baking and in animal feed (CABI 2021). China and Korea are among the world’s largest producers of chestnuts, with Italy, Spain, Portugal, France and Greece the principal European producers (LOINC 2021).

Route of Exposure

Main

The main route of exposure is inhalation.

Detection

Chestnut pollen may be sampled using a vacuum air sampler such as the Burkard spore trap (3).

Clinical Relevance

Chestnut pollen allergy is associated with allergic rhinoconjunctivitis and asthma (4).

Prevention and Therapy

Allergen immunotherapy

Immunotherapy with the reference allergen Bet v 1 (birch pollen) induced highly variable repertoires of cross-reactive IgG1 and IgG4 antibodies to other members of the birch-homologous group, including chestnut pollen (7). Current data suggest that chestnut pollen allergy does not show sufficient immunological cross-reactivity to respond successfully to immunotherapy (8).

Prevention strategies

Avoidance

Allergenic pollen calendars are a simple method for forecasting chestnut pollen counts, as demonstrated using data from eight collection stations in South Korea over 10 years (3). Artificial neural networks (a type of computational learning) have proved to be a valid tool for predicting Castanea pollen concentration for one day ahead and, less reliably, for two and three days ahead of exposure (1).

Molecular Aspects

Allergenic molecules

Allergenic molecules of Castanea sativa (adapted from EAAC Molecular Allergology User’s Guide 2016) (9)

Allergen name	Biochemical name
Cas s 1	PR-10, Bet v 1 family member
Cas s 5	Chitinase
Cas s 8	Non-specific lipid transfer protein type 1
Cas s 9	Cytosolic class 1 small heat shock protein

Cas s 1 is the major pollen allergen of Castanea sativa. The major pollen allergens of the Fagales order belong to the pathogenesis-related protein class 10 (PR-10), which includes a large group of aeroallergens (10). All major allergens of the birch-homologous group of pollens share structural homology and biochemical properties with the major birch pollen allergen, Bet v 1 (4, 7).

Cross-reactivity

The European Medicines Agency includes Castanea sativa in the birch-homologous group of tree pollens. The major allergen of chestnut pollen (Cas s 1) demonstrates a 75% (N-terminal) amino acid sequence homology with Bet v 1, the major allergen of birch pollen (4). The earlier pollen seasons for hazel and alder may act to prime patients for birch pollen allergy, followed by allergic responses to beech and chestnut pollen (4).

In a study of 17 Bet v 1-sensitized, birch pollen-allergic patients, all subjects displayed IgE reactivity with the most common isoforms of Cas s 1 (7). However, a larger study examining 397 birch-allergic patients before and after treatment with standardized quality tree sub-lingual immunotherapy (SLIT) tablets did not find significant IgE or IgG4 cross-reactivity to chestnut, suggesting that chestnut pollen is not immunologically part of the birch-homologous group (8).

Compiled By

Author: RubyDuke Communications

Reviewer: Dr. Christian Fischer

Last reviewed:January 2022

References

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