t3 Common silver birch

Allergens within Tree Pollens

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  • Latin name: Betula verrucosa
  • Family: Betulaceae
  • Source material: Pollen
A tree species producing large amounts of pollen, which often induces hayfever, asthma and conjunctivitis in sensitised individuals.

Allergen Exposure

Geographical distribution
Common Silver Birch is a single-stemmed, deciduous tree up to about 25 metres. The bark is smooth and slivery white, becoming black and fissured into rectangular bosses.
 
Common Silver Birch is native and common in most of Europe, northwest Africa and western Siberia, but absent in the southernmost parts of Europe. It is the most common tree found in Scandinavia and the Alps and a potent pollen producer in those areas. The similar B. pubescens may be found in the more northern areas of Europe and particularly in the mountains, forming extensive woods.  There are closely related species in East Asia and North America. The genus has about 40 species distributed in the northern temperate regions.
 
Common Silver Birch flowers in late spring, usually at the same time as the leaves appear, but in North America it blooms early in spring and occasionally flowers again in late summer or fall. The bloom time is usually short. These trees are wind-pollinated.
 
Environment
Birch occurs in woods, particularly where the soil is lighter. It often grows in heath lands and clearings and is also planted in gardens.
 
Allergens
To date, the following allergens have been isolated from the Common Silver Birch tree:
  • Bet v 1
  • Bet v 2
  • Bet v 3
  • Bet v 4
  • Bet v 5
  • Bet v 7
and a number of isoforms, e.g., Bet v 1n and Bet v 1d. Bet v 1 is the major Birch pollen allergen. Bet v 2 is a profilin (1-6).
 
Bet v 1 is recognized by IgE from about 95% of Birch-allergic patients, Bet v 2 and Bet v 3 from 10%, and Bet v 5 from 32%, whereas Bet v 4 reacts with serum IgE from approximately 20% of individuals allergic to pollen. (1-5).

Potential Cross-Reactivity

Cross-reactivity between pollens from species within the Betulaceae family or belonging to closely related families can be expected (7). Cross-reactivity between Birch pollen and alder pollen has been demonstrated in individuals with allergic rhinitis due to Birch pollen (8).
 
A common panallergen, profilin is present in Common Silver Birch, peach and apple, and this may result in crossreactivity between these, even though patients have never been exposed to Birch (9). Cross-reactivity has also been frequently observed to other substances containing profilin, e.g., hazelnut, ragweed pollen, mango, mugwort pollen, timothy grass pollen, celery, carrot, peanut, paprika, anise, fennel, coriander and cumin (10-14). The major allergens in apple, pear, apricot and sweet cherry are structural homologs to the Birch pollen major allergen Bet v 1 (15).

Clinical Experience

IgE mediated reactions
Birch pollen is highly allergenic and allergic reactions, e.g., asthma, allergic rhinitis and conjunctivitis have been described (16).
 
Cross-reactivity between Birch and food may result in symptoms of Oral Allergy Syndrome in Birch-sensitised individuals (17). Symptoms of food allergy in Birch pollinosis patients are usually mild and restricted to the oral cavity. On the other hand, while allergy to a food, e.g., hazelnuts, without concomitant pollinosis is less common, symptoms tend to be more severe and are often systemic (17).
 
In a study on patients with seasonal rhinitis, it was found that Birch, beech, alder, hazel and oak pollens are most important as causes of springtime hay fever (16).
 
Other reactions
Birch pollen-related foods trigger atopic dermatitis in patients with specific cutaneous T-cell responses to Birch pollen antigens (18).

Compiled by Dr Harris Steinman, harris@zingsolutions.com

References:

    1. Breiteneder H, Pettenburger K, Bito A, Valenta R, Kraft D, Rumpold H, et al. The gene encoding for the major birch pollen allergen Bet v 1 is highly homologous to a pea disease resistance response gene. EMBO J 1989;8:1935-8 
    2. Valenta R, Duchene M, Pettenburger K, Sillaber C, Valent P, Bettelheim P, et al. Identification of profilin as a novel pollen allergen; IgE autoreactivity in sensitised individuals. Science 1991;253-557-60 
    3. Seiberler S, Scheiner O, Kraft D, Lonsdale D, Valenta R. Characterization of a birch pollen allergen, Bet v III, representing a novel class of Ca2+ binding proteins: specific expression in mature pollen and dependence of patient's IgE binding on protein-bound Ca2+. EMBO J 1994;13:3481-6 
    4. Engel E, Richter K, Obermeyer G, Briza P, Kungl AJ, Simon B, et al. Immunological and biological properties of Bet v 4, a novel birch pollen allergen with two EF-hand calcium binding domains. J Biol Chem 1997;272:28630-7 
    5. Karamloo F, Schmitz N, Scheurer S, Foetisch K, Hoffman A, Haustein D, Vieths S. Molecular cloning and characterization of a birch pollen minor allergen, Bet v 5, belonging to a family of isoflavone reductase-related proteins. J Allergy Clin Immunol 1999;104(5):991-999 
    6. Cadot P,Diaz JF, Proost P, Van DJ, Engelborghs Y, Stevens EA, Ceuppens JL. Purification and characterization of an 18-kd allergen of birch (Betula verrucosa) pollen: identification as a cyclophilin. J Allergy Clin Immunol 2000;105 (2 Pt1):286-291 
    7. Yman L. Botanical relations and immunological cross-reactions in pollen allergy. Pharmacia Diagnostics AB. Uppsala. Sweden. 1978: ISBN 91-7260-511-1 
    8. Maguchi S, Takagi S, Yoshida M, Fukuda S, Inuyama Y. Birch pollen nasal allergy in Sapporo and its cross reactivity with alder pollen. [Japanese] Nippon Jibiinkoka Gakkai Kaiho 1993;96(1):1-9 
    9. van Ree R, Fernandez Rivas M, Cuevas M, van Wijngaarden M, et al. Pollen-related allergy to peach and apple: an important role for profilin. J Allergy Clin Immunol 1995;95(3):726-34 
    10. Paschke A, Kinder H, Zunker K, Wigotzki M, Steinhart H, Wessbecher R, Vieluf I. Characterization of cross-reacting allergens in mango fruit. Allergy 2001;56(3):237-42 
    11. Calkhoven PG, Aalbers M, Koshte VL, et al. Cross-reactivity among birch pollen, vegetables and fruits as detected by IgE antibodies. Allergy 1987;42:382-390 
    12. Pastorello, EA, Farioli, L, Pravettoni, V, Mambretti, M et al. A RAST-inhibition study of crossreactivity between peach and plum, apricot, birch, timothy. Schweiz med Wschr 1991;121:P2 290.Suppl 40: 1&II 
    13. Helbling A, Lopez M, Schwartz HJ, Lehrer SB. Reactivity of carrot-specific IgE antibodies with celery, apiaceous spices, and birch pollen. Ann Allergy 1993;70(6):495-9 
    14. Asero R. Relevance of pollen-specific IgE levels to the development of Apiaceae hypersensitivity in patients with birch pollen allergy. Allergy 1997;52(5):560-4 
    15. Rodriguez J, Crespo JF, Lopez-Rubio A, De La Cruz-Bertolo J, et al. Clinical cross-reactivity among foods of the Rosaceae family. J Allergy Clin Immunol 2000;106(1 Pt 1):183-9 
    16. Jung K, Schlenvoigt G, Jager L. Allergologic-immunochemical study of tree and bush pollen. II--Study of the sensitization spectrum of patients with seasonal rhinitis in the spring. Allerg Immunol 1987;33(4):215-21 
    17. Akkerdaas J, Hafle S, Aalberse R, van Ree R. Characterization of non-pollen-related hazelnut allergens. AAAAI 56th Annual Meeting March, 2000 
    18. Reekers R, Busche M, Wittmann M, Kapp A, Werfel T. Birch pollen-related foods trigger atopic dermatitis in patients with specific cutaneous T-cell responses to birch pollen antigens. J Allergy Clin Immunol 1999;104(2 Pt 1):466-472

2002



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