ABSTRACT
The role of T-Helper 2 [Th2] cells in the pathogenesis of allergy and asthma has been well described. However, the immunologic mechanisms that down modulate and protect against the development of these disorders are poorly characterized. A spectrum of CD4+ T cells, including, FOXP3-positive CD4+CD25+ T regulatory cells [Tregs] might play a critical role in regulating these diseases. To investigate the role of CD4+CD25high FoxP3 Tregs in the pathogenesis of pediatric asthma. The study included 24 asthmatic children, 12 had mild intermittent asthma and 12 were of severe persistent asthma . In addition, 12 healthy subjects were used as controls. All patients were subjected to clinical examination and laboratory investigations including complete blood count with differential leucocytic and absolute eosinophilic count, serum total IgE level by ELIZA and flow cytometry was used to study the frequency of Tregs in peripheral blood lymphocytes of all studied groups using specific markers: cell-surface CD25 and CD4 expression and cytoplasmic FoxP3 expression. It was noticed a significant decrease in CD4+CD25+ % and CD4+CD25 high % in both mild intermittent cases and severe persistent asthmatic patients when compared to healthy controls. FoxP3 expression in Tregs was significantly lower in CD4+CD25high T-cells of mild asthmatic patients when compared to control group. While the FoxP3 expression in Tregs was non- significantly lower in CD4+CD25high T-cells of severe asthmatic patients .Tregs cells % was correlated significantly with mild asthma .While it did not show correlation with severe asthma . An inverse correlation between FoxP3 protein expression was revealed within CD4+CD25high T-cells and total serum IgE when analyzed for all subjects. However, when correlation analysis was performed in each studied group separately, no significant correlation was found between FoxP3 expression and total serum IgE levels and there was no correlation between FoxP3 protein expressions within CD4+CD25high T-cells and eosinophilic count was noticed. The correlation of CD4+CD25high FoxP3 Tregs with asthma pathogenesis indicates that it is important to evaluate Tregs in allergic asthmatic children. Greater understanding of the molecular and immunological mechanisms underlying the CD4+CD25high FoxP3 Tregs might contribute the development of treatment modalities to influence disease processes of bronchial asthma in children as a future therapeutic target