Allergenic molecules
Allergenic molecules of Castanea sativa (adapted from EAAC Molecular Allergology User’s Guide 2016) (9)
Allergen name
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Biochemical name
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Cas s 1
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PR-10, Bet v 1 family member
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Cas s 5
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Chitinase
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Cas s 8
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Non-specific lipid transfer protein type 1
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Cas s 9
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Cytosolic class 1 small heat shock protein
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Allergen name
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Biochemical name
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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).
