Complex IgE sensitization patterns in ragweed allergic patients: Implications for diagnosis and specific immunotherapy

Background: Ragweed (Ambrosia artemisiifolia) is one of the most important allergen sources, worldwide, causing severe respiratory allergic reactions in late summer and fall, in sensitized patients. Amb a 1 has been considered as the most important allergen in ragweed but 12 ragweed pollen allergens are known. The aim of our study was to investigate IgE reactivity profiles of ragweed allergic patients and to associate them with clinical symptoms.

Methods: IgE sensitization profiles from clinically well-characterized ragweed allergic patients (n = 150) were analyzed using immunoblotted ragweed pollen extract. Immunoblot inhibition experiments were performed with two Amb a 1 isoforms and CCD markers and basophil activation experiments were performed with IgE serum before and after depletion of Amb a 1-specific IgE.

Results: By IgE-immunoblotting 19 different IgE reactivity patterns with and without Amb a 1-sensitization were found. The majority of patients (>95%) suffered from rhino-conjunctivitis, around 60% reported asthma-like symptoms and about 25% had skin reactions. Patients with complex IgE sensitization profiles tended to have more clinical symptoms. Serum with and without Amb a 1-specific IgE induced basophil activation.

Conclusions: Ragweed pollen allergic patients exhibit complex IgE reactivity profiles to ragweed allergens including Amb a 1 isoforms and cross-reactive carbohydrates indicating the importance of Amb a 1 isoforms and additional allergens for diagnosis and allergen-specific immunotherapy of ragweed allergy.