Background: A 29-year-old female presented with a first-time anaphylactic reaction. History revealed the intake of "Schwarzbeernocken", a Tyrolean speciality containing blueberries, 1 hour prior to the onset of symptoms. We aimed to identify the culprit allergen. Methods: Serum from a blueberry allergic donor was studied for IgE reactivity to blueberry, mugwort (Artemisia vulgaris) and birch (Betula verrucosa) pollen extract in IgE immunoblot experiments. IgE inhibition experiments and N-terminal sequencing were performed to further identify the putative blueberry allergen. In addition, blueberry extract was evaluated for cross-reactive allergens with sera from a Bet v 1- and a mono-sensitized mugwort pollen-allergic patient. Results: Blueberries contain a 9 kDa allergen which cross-reacts with Pm p 3, the nonspecific lipid transfer protein from peach, and shows sequence homology with cabbage lipid transfer protein. No allergen homologous to Bet v 1 could be identified in blueberries. Conclusion: Blueberry lipid transfer protein represents a relevant food allergen which can cause severe anaphylactic reactions. However, blueberries apparently do not contain any Bet v 1-homologue. This protein family is found in many other foods and known as the most common cause of oral allergy syndrome in the Northern hemisphere.

Background: Allergen-specific subcutaneous immunotherapy (SCIT) is an antigen-specific therapy of IgE-mediated allergies. In the present study, we analyze the epitope specificities of antibody responses induced by SCIT with allergen extracts from pollen of trees belonging to the order Fagales (birch, alder, hazel) adsorbed onto aluminum hydroxide. Methods: The IgE, IgG1–4 and IgA responses to defined recombinant allergens (birch pollen: Bet v 1; alder pollen: Aln g 1; hazel pollen: Cor a 1; apple: Mal d 1) as well as to Bet v 1-derived recombinant fragments and synthetic peptides were analyzed in sera from patients who had undergone SCIT for different periods of time. Results: Long-term SCIT (>1 year; cumulative dose >1,000,000 SQ units) induced more pronounced IgG1, IgG2 and IgG4 responses to Bet v 1 and Bet v 1-related allergens according to the degree of sequence homology (Bet v 1>Aln g 1>Cor a 1>Mal d 1) than short-term SCIT (<1 year; cumulative dose <1,000,000 SQ units). In contrast to patients treated for <1 year, patients treated for >1 year mounted distinct IgG1, IgG2 and IgG4 responses against sequential Bet v 1 epitopes. No relevant allergen-specific IgA or IgG3 responses were induced by short- or long-term SCIT. Using a competitive ELISA assay, it could be shown that serum IgG from patients undergoing long-term SCIT inhibited IgE reactivity to Bet v 1 better than IgG from patients undergoing short-term SCIT. Conclusion: SCIT with allergen extracts adsorbed onto aluminum hydroxide induces IgG responses against new epitopes that block IgE binding and cross-react with structurally related allergens depending, among other factors, on duration of treatment and cumulative injected dose.

BACKGROUND:Beech and oak pollen are potential allergen sources with a world-wide distribution.OBJECTIVE:We aimed to characterize the allergen profile of beech and oak pollen and to study cross-reactivities with birch and grass pollen allergens.METHODS:Sera from tree pollen-allergic patients with evidence for beech and oak pollen sensitization from Basel, Switzerland, (n=23) and sera from birch pollen-allergic patients from Vienna, Austria, (n=26) were compared in immunoblot experiments for IgE reactivity to birch (Betula pendula syn. verrucosa), beech (Fagus sylvatica) and oak (Quercus alba) pollen allergens. Subsequently, beech and oak pollen allergens were characterized by IgE inhibition experiments with purified recombinant and natural allergens and with allergen-specific antibody probes. Birch-, beech- and oak pollen-specific IgE levels were determined by ELISA.RESULTS: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. IgE levels to beech and oak pollen allergens were lower than those to birch pollen allergens.CONCLUSION: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.