In Genoa, the allergenic pollen landscape in spring is dominated by alder, various species, including and species play only a minor role . beech Fag s 1, were identified in the respective pollen extracts, cloned and produced as recombinant proteins in allergic donors. Strong IgE binding was observed for and allergens, however, cross-reactivity between the two subfamilies was limited as explored by inhibition experiments. In contrast, IgE binding to members of the could be strongly inhibited by serum pre-incubation with allergens of the subfamily. Conclusions and Clinical Relevance The data suggest that Bet v 1-like allergens of the and subfamily might have the potential to induce IgE antibodies with different specificities, while allergic reactions towards allergens are the result of IgE cross-reactivity. pollen allergies represent the main cause of spring pollinosis in the temperate climate zone of the Northern hemisphere. The botanical order of is classified into 8 families, 55 genera and 1877 species . These families are (southern beech family), (beech family, including the genera beech, oak and chestnut), (walnut family), Myricaceae (bayberry family), (rhoiptelea family), (ticodendron family), (birch family) and (she-oak family) . The family can be further divided into allergies are dominated by cross-reactive allergens belonging to the PR-10 proteins. The best-studied allergenic representative of this family is Bet v 1, the birch pollen major allergen. Depending on the observed population, between 62% and 100% of birch Triisopropylsilane pollen-sensitized individuals show IgE reactivity towards the molecule , also in areas where no direct birch pollen exposure is possible [10, 11]. In addition, several allergenic Bet v 1 homologues have been identified in pollen of related trees, and were Triisopropylsilane cloned, produced and characterized immunologically [12C14]. Open in a separate window Fig. 1 Schematic overview of the botanical order of trees, which have been reported to be implicated with allergic diseases are indicated with *, allergenic trees with pollen allergens acknowledged by the WHO/IUIS allergen nomenclature subcommittee are indicated with **. The graph is adapted from Li et al. . Not all airborne pollen-producing species initiate or elicit allergic reactions to the same extent. These differences might be related to the amount of pollen released by the different species, differences in aerodynamic properties of the pollen, the flowering periods of the respective species or the content of allergenic protein in the pollen. For example, alder pollen represents a rather potent source of allergenic pollen by reaching high numbers of pollen counts in winter . However, the allergenic potential of alder is limited due to the early flowering period where people Rabbit Polyclonal to HTR5A normally do not spend much time outdoors. Hazel, hornbeam, oak, beech and chestnut produce high pollen counts, especially in the southern regions of Europe, but still their sensitizing potential is considered significantly lower when compared with birch pollen . Thus, it is widely accepted that pollen of these aforementioned species act as supporting factors for allergic sensitization, while birch Bet v 1 is Triisopropylsilane most likely initiating the disease. As acknowledged, within the last years, evidence is accumulating that also other pollen-derived Bet v 1 homologues might have the potential to sensitize atopic individuals [10, 12]. To further address this question, we took advantage of a large panel of already available recombinant allergens from alder, birch, hazel, hornbeam and oak. In addition, the Bet v 1 homologous allergens from beech, chestnut and hop-hornbeam [4, 17, 18] were identified, produced and characterized. The whole panel of allergens was immobilized on slides for IgE-binding studies in microarray format and IgE inhibition studies with patients sera from three distinct geographical areas showing different distribution were performed. The sera were tested with Bet v 1, as representative member of the and Ost c 1, as representative member of the families, to address the question of cross-reactivity vs. co-sensitization for allergies. Methods Patients and sera pollen allergic patients were selected based on case history, positive skin prick test and IgE detection using Immuno Solid-phase Allergen Chip (ISAC) 103 (Phadia Multiplexing Diagnostics GMBH, Vienna, Austria)  according to previously reported protocols . Sera (= 25) were obtained from the Allergy Unit at the University Hospital in Genoa, Italy, from the Center for Molecular Allergology at IDI-IRCCS in Rome, Italy, and from the Allergieambulatorium Reumannplatz, Vienna, Austria (Table 1). According to pollen data, it is suspected that subjects recruited in Genoa were primarily exposed to pollen from hop-hornbeam and other species but not to birch pollen, subjects recruited in Rome to pollen from other species but not to that from hop-hornbeam and birch and subjects recruited in Vienna primarily to birch pollen [15, 20]. The study was approved by the Institutional Review Board (n. 106-CE-2005), and signed informed consents were obtained. Table 1 Total IgE was measured.