Abundant CD4+FOXP3+ regulatory T cells fail to suppress the proliferation of T cells in patients with Turner syndrome

Results TS patients exhibited a higher frequency of CD4FOXP3 Tregs among their lymphocytes (mean 2.06 vs. 1.52%, P = 0.005) and FOXP3 Tregs among their CD4 T cells (7.44 vs. 4.19%, P < 0.001) compared to controls. The expression of inhibitory CTLA-4 in the Tregs of TS patients was also significantly higher (mean fluorescence intensity = 214.1 vs. 184.6, P = 0.003). The frequency of Tregs expressing GITR, CXCR3, and CCR4CCR6 was comparable between the two groups. However, the ability of Tregs to suppress the in vitro proliferation of autologous CD4 CD25 T cells was significantly impaired in TS patients compared to controls (P < 0.05 at a 0.1:1 ratio of Tregs to target cells, P < 0.01 at 0.25:1, 0.5:1, and 1:1).