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Abstract

Asthma and allergy are major health problems in most modern so-cieties, and numerous studies indi-cate that allergic diseases have been increasing during the past decades. The growing prevalence of allergies in industrialized countries may be linked, beside other factors, to air pollution. Allergenic proteins are efficiently nitrated and cross-linked by atmospheric ozone and nitrogen dioxide (O3/NO2) or physiologically relevant peroxynitrite (ONOO-), and the modifications occur primarily at tyrosine residues. In several studies, modified food and airborne allergens showed an altered allergenic potenti-al, but the underlying chemical and immunological mechanisms remain unclear. Here, the major birch pollen allergen Bet v 1 and the major grass pollen allergen Phl p 5 were exposed to atmospherically relevant concent-rations of ozone and nitrogen dioxide (O3/NO2) and different levels of per-oxynitrite (ONOO-). To determine the degree of tyrosine nitration and tyrosine cross-linked dimeric and oligomeric allergens, reversed-phase (C18) and size-exclusion chromato-graphy (SEC) coupled to a diode ar-ray detector (DAD), and SDS-PAGE were used. IgE binding ELISA using sera of birch and grass pollen allergic patients assessed altered immunity of the modified allergens. To study parts of the innate immune respon-se, TLR4 activation were measured using respective reporter cell lines. Modified Bet v 1 (ONOO-) leads to higher IgE binding in almost all pati-ents, whereas modified Phl p 5 does not show higher IgE binding. In con-trast, ONOO- modification of Phl p 5 leads to higher TLR4, while modified Bet v 1 induced no activation. Thus, modification of Bet v 1 seems to al-ter IgE epitopes, which is in line with earlier studies, whereas the modifica-tion of Phl p 5 affects innate immu-ne reactions, rather than IgE epitope binding. Therefore, the two allergens alter immune reactions by different modes of actions, either by the innate or adaptive part of immunity.