T Regulatory Cells Response to Allergen Specific Immunotherapy in Patients with Allergic Airway Diseases: A Prospective Study.

Forkhead box P3 (FoxP3) T regulatory (Treg) cells modulate the immune system by blocking other types of T-cells. They maintain tolerance to self-antigens and help in inducing tolerance to foreign antigens. A deregulation of FoxP3 Tregs seems to play an important role in allergic disorders. The aim of this work was to study the response of FoxP3 Treg cells and their FoxP3 expression in patients, attending the Allergy Unit and the Chest Outpatient Clinic, Faculty of Medicine, Zagazig University, with allergic airway diseases, before and 1 year after receiving subcutaneous allergen specific immunotherapy (SIT). This prospective study was carried out on 25 patients with allergic airway diseases, confirmed by positive skin test, and that showed clinical improvement one year after SIT. All cases were subjected to total immunoglobulin E quantitation by ELISA. FoxP3 Treg cells frequency and FoxP3 relative fluorescence intensity, as an indicator of Tregs function, were assessed by flowcytometry. The results were compared before and after SIT. Twenty five age and sex matched apparently healthy volunteers were enrolled as controls. Our findings demonstrated that in comparison to the control group, the count of FoxP3 T regulatory cells was higher; however, the function was lower among the enrolled patients (P= 0.007 and P< 0.001, respectively). When FoxP3 Tregs were compared in the patients before and one year after SIT, it was found that both the count and FoxP3 expression showed statistically significant increase (P< 0.001). An inverse correlation was found between FoxP3 Tregs count and FoxP3 expression. It is concluded that patients with allergic airway diseases have increased number of FoxP3 Treg cells but with defective function. SIT plays a role in increasing the number of FoxP3 Tregs and improving their suppressive function, which leads to control of airway inflammation and thus clinical improvement.