Effects of iodine-131 radiotherapy on Th17/Tc17 and Treg/Th17 cells of patients with differentiated thyroid carcinoma.

T helper 17 (Th17), T cytotoxic 17 (Tc17) and regulatory T (Treg) cells serve important roles in a number of inflammatory and autoimmune diseases. The aim of the present study was to examine the distribution of Th17, Tc17 and Treg cells in patients with differentiated thyroid cancer (DTC) prior to as well as 7, 30 and 90 days following radioactive iodine-131 (131I) therapy, and to elucidate the probable effects of 131I therapy on Th17/Tc17 and Treg/Th17 cells in patients with DTC. A total of 40 patients with DTC (26 female; 14 male) between the ages of 24 and 72 years, as well as 13 age- and sex-matched healthy subjects were included in this study. The number of Th17, Tc17 and Treg cells in the peripheral blood of patients with DTC and of healthy Controls were assessed by flow cytometry. Th17 and Tc17 cells were counted as percentages of the number of CD3+ T cells; Treg cells were counted as a percentage of the number of CD4+T cells. In addition, the serum levels of interleukin (IL)-17, IL-23, IL-10 and transforming growth factor (TGF)-β1 were examined by ELISA. The frequencies of Th17, Tc17 and Treg cells, as well as the serum levels of IL-17, IL-23, IL-10 and TGF-β1 were significantly elevated in patients with DTC compared with healthy Controls, whereas 131I therapy significantly decreased them. In addition, elevated Th17/Tc17 ratio and reduced Treg/Th17 ratio were observed in patients with DTC at day 0, however, these ratios returned to normal levels following 131I therapy for 90 days as compared with healthy Controls. Notably, Th17/Tc17 and Treg/Th17 ratios varied following 131I therapy for 7 and 30 days. In addition, a strong positive correlation between Th17 and Tc17 cells was observed in the healthy Controls and patients with DTC that received 131I treatment for 90 days, whereas a weak positive correlation between Th17 and Treg cell levels was identified in the healthy Controls and no obvious correlation between Th17 and Treg cells was observed in all patients with DTC pre- and post-131I therapy during the entire treatment period. These data suggested a significant involvement of Th17, Tc17 and Treg cells in the pathology of DTC. Restoring the balance of these cells may contribute to the recovery of patients with DTC following 131I therapy.