Dictionary of Allergies .. Birch pollen

Birch pollen is the major allergen in pollinosis in northern Japan. IgE reactivity to individual birch pollen allergens has been shown to differ between populations of birch pollen-allergic patients living in different countries [1]. The major allergen of birch pollen, Bet v 1, and its homologous proteins in food of plant origin (Mal d 1 in apples, Pru av 1 in cherries, and Cor a 1 in hazelnuts), were identified as the most important mediators of crossreactivity. Profilin, first identified as the birch pollen allergen Bet v 2 , was recognized as another important crossreacting structure. In addition, the recently identified birch pollen allergens Bet v 6, a phenyl coumaran benzylic ether reductase, and Bet v 8, a pectin esterase, may also be involved in similar cross-reactivity. Commercial birch pollen extracts exhibit a considerable variability regarding allergen contents and hence deliver varying in vivo test results. These problems might be overcome with recombinant allergen-based preparations [2].

ecombinant DNA technology has the potential to produce allergen-specific immunotherapy vaccines with defined composition. The rBet v 1-based vaccine was safe and effective in treating birch pollen allergy, and induced a highly specific immune response[3].

In many cases, patients allergic to birch pollen also show allergic reactions after ingestion of certain fruits or vegetables. This observation is explained at the molecular level by cross-reactivity of IgE antibodies induced by sensitization to the major birch pollen allergen Bet v 1 with homologous food allergens. As IgE antibodies recognize conformational epitopes, a precise structural characterization of the allergens involved is necessary to understand cross-reactivity and thus to develop new methods of allergen-specific immunotherapy for allergic patients[4].

Beech and oak pollen contain allergens that cross-react with the birch pollen allergens Bet v 1, Bet v 2 and Bet v 4 and with the berberine bridge enzyme-like allergen Phl p 4 from timothy grass pollen. Sera from Swiss and Austrian patients exhibited similar IgE reactivity profiles to birch, beech and oak pollen extracts[5]. IgE reactivity to beech pollen is mainly due to cross-reactivity with birch pollen allergens, and a Phl p 4-like molecule represented another predominant IgE-reactive structure in oak pollen. The characterization of beech and oak pollen allergens and their cross-reactivity is important for the diagnosis and treatment of beech and oak pollen allergy[5].

Pollen-related food allergy to fresh fruits and vegetables is a well-known clinical phenomenon. Bet v 1, the major birch pollen allergen, has been cloned and shows homologies to various food allergens (e.g. hazelnut, apple, celery, tomato). Allergy to profilin Bet v 2 was also described in 10-15% of patients sensitized to birch pollen[6]. See: Birch, common silver

References.

2. Focke M, Marth K, Valenta R. Molecular composition and biological activity of commercial birch pollen allergen extracts. Eur J Clin Invest. 2009 May;39(5):429-36.

3. Pauli G, Larsen TH, Rak S, Horak F, Pastorello E, Valenta R, Purohit A, Arvidsson M, Kavina A, Schroeder JW, Mothes N, Spitzauer S, Montagut A, Galvain S, Melac M, André C, Poulsen LK, Malling HJ. Efficacy of recombinant birch pollen vaccine for the treatment of birch-allergic rhinoconjunctivitis. J Allergy Clin Immunol. 2008 Nov;122(5):951-60 Erratum in: J Allergy Clin Immunol. 2009 Jan;123(1):166. Valenta, Rudolph [corrected to Valenta, Rudolf].

4. Berkner H, Neudecker P, Mittag D, Ballmer-Weber BK, Schweimer K, Vieths S, Rösch P. Cross-reactivity of pollen and food allergens: soybean Gly m 4 is a member of the Bet v 1 superfamily and closely resembles yellow lupine proteins. Biosci Rep. 2009 Jun;29(3):183-92.

5. Egger C, Focke M, Bircher AJ, Scherer K, Mothes-Luksch N, Horak F, Valenta R. The allergen profile of beech and oak pollen. Clin Exp Allergy. 2008 Oct;38(10):1688-96. Epub 2008 Aug 25

6. Cudowska B, Kaczmarski M. Diagnostic value of birch recombinant allergens (rBet v 1, profilin rBet v 2) in children with pollen-related food allergy. Rocz Akad Med Bialymst. 2004;49:111-5.