Role of Foxp3 and regulatory CD4+CD25+ T-lymphocytes in bronchial asthma

Regulatory T cells (Tregs) are thought to have a critical role in the suppression of immune responses. In addition to the prevention of the development of autoimmunity, they are thought to have a role in the prevention of allergic responses to environmental allergens. Foxp3 is transcription factor (Foxp3), which is predominantly expressed by CD4+ CD25+ T cells, and may correlates with the suppressive activity of these cells. This study assesses the immunoregulatory role of CD4+CD25+ T-lymphocytes in peripheral blood of asthmatic children and possible role of Foxp3 mRNA expression. The study included thirty children, 10 with acute asthmatic exacerbation, 10 during rest state with no asthma manifestation and 10 apparently healthy children. T-regs, and Foxp3 mRNA were investigated using Flowcytometry and RT-PCR respectively. Early morning sputum was also collected for determination of eosinophillia. Significant increase in the percent of CD4+CD25+ was found in acute asthmatic as compared to stable asthmatic cases (23.3 +/- 3.74% vs 13.97% +/- 1.18%), and in acute asthmatic group than control group (13.97% +/- 1.18% vs 8.12 +/- 1.65%), (P < 0.001). Similarly, significant increase in Foxp3 mRNA expression was found in acute asthmatic cases as compared to stable and control children (P < 0.001). A significant positive correlation was found between Foxp3 mRNA expression and the percent of CD4+CD25+ T cells in all studied groups (r = 0.91 P = 0.01). It is concluded that regulatory CD4+CD25+ T-cells may play a critical role in maintaining suppression and protection against allergic bronchial asthma and that Foxp3 may be important in the development of these cells.