Genetic and environmental factors are responsible for running allergic diseases. The aim of this study was to compare the values of total-(t-IgE) and allergen-specific IgE (s-IgE) to Ambrosia artemisiifolia L. (Amb a) in children with sensitization to Amb a during ragweed pollination season, who experienced seasonal symptoms of allergic rhinitis (rhinorrhea, post-nasal drip, nasal congestion, itching, sneezing) and asthma (coughing, especially at night, wheezing, shortness of breath, chest tightness). Ragweed pollen grains were collected in Virovitica (rural area) and Zagreb (urban area)-cities with the same geographical width and elevation-during ragweed pollination seasons (July-October in 2006 and 2007), and their count was estimated. Concentration of t-IgE and s-IgE in pollination season was determined in serum of children with symptoms of allergic diseases. The total count of ragweed pollen grains (PG) differed significantly between Virovitica and Zagreb in both years, 2006. and 2007. In Virovitica it was significantly greater than in Zagreb. There was no statistically significant seasonal difference in both, t-IgE and s-IgE, respectively. No correlation was found between pollen grain count and the concentration of IgE's. To clarify the induction of IgE synthesis in children with sensitization to Amb a, further studies are needed.

Dysregulation of inflammatory mediators is characteristic for chronic inflammation in allergy. The aim was to determine the values of serum IL-17 and IL-5 in ragweed-sensitized children. The study included children analyzed during the ragweed pollen season compared to children analyzed out of season. Serum total IgE, specific IgE, and eosinophil cationic protein (ECP) were determined by fluoroimmunoassay while the concentrations of IL-5 and IL-17 were determined by flow cytometry. Patients evaluated during the pollen season, have higher values of total and specific IgE, eosinophil and neutrophil count than patients studied outside the pollen season. There was no statistically significant seasonal and out of season differences for the concentration of IL-17, IL-5, and ECP. Natural exposure to ragweed pollen allergen was not crucial for the induction of increased IL-17 and IL-5 synthesis, and factors other than allergen exposure should be investigated, especially in longitudinal studies of patients.