BackgroundPrimary immune thrombocytopenia (ITP) is an autoimmune heterogeneous disorder that is characterized by decreased platelet count. Regulatory T (Treg) cells and T helper type 17 (Th17) cells are two subtypes of CD4+ T helper (Th) cells. They play opposite roles in immune tolerance and autoimmune diseases, while they share a common differentiation pathway. The imbalance of Treg/Th17 has been demonstrated in several autoimmune diseases. In this study, we aimed to investigate the ratio of the number of Treg cells to the number of Th17 cells in ITP patients and evaluate the clinical implications of the alterations in this ratio.MethodsThirty adult patients with newly diagnosed ITP enrolled in this study. Twelve patients had been clinically followed up for 12 months. The percentages of CD4+CD25hiFoxp3+ Treg cells and CD3+CD4+IL-17-producing Th17 cells in these patients and healthy controls (n = 17) were longitudinally analyzed by flow cytometry.ResultsThe percentage of Treg cells in ITP patients was significantly lower than that of healthy controls, and the percentage of Th17 cells increased significantly at disease onset. The ratio of Treg/Th17 correlated with the disease activity.ConclusionThe ratio of Treg/Th17 might be relevant to the clinical diversity of ITP patients, and this Treg/Th17 ratio might have prognostic role in ITP patients.

Primary immune thrombocytopenia (ITP) is an autoimmune heterogeneous disorder. Excessive activated CD4(+) T effector cells (Teffs) and compromised regulatory T cells (Tregs) were reported in ITP patients, yet little is known about the mechanisms. Interleukin-10 (IL-10) is an important regulatory cytokine of Tregs in inflammatory condition. It has been recently highlighted that IL-10-producing Tregs contribute to the effective controls of several autoimmune diseases. Hence this study was aimed to examine the role of IL-10 produced by Tregs in newly diagnosed ITP patients. Newly diagnosed ITP patients and healthy volunteers were enrolled to assess the numbers of peripheral Th1, Th17 cells and Tregs. CD4(+)CD25(-)Teffs and CD4(+)CD25(+)Tregs were purified. CD4(+)CD25(-)Teffs, labeled with CFSE, were cultured alone or with Tregs for 5 days, and the supernatants were then collected for IL-10 concentration test. The role of IL-10 in Tregs' inhibitory function was also determined. In ITP patients, Teffs were excessively activated, while the Tregs were numerically and functionally impaired. The percentages of IL-10(+) Tregs in Tregs' population were found elevated dramatically in ITP patients but decreased in the remitted patients. The IL-10 concentrations in the cultured supernatant were decreased in ITP patients but elevated in the remitted patients. Furthermore, the IL-10 secretion by Tregs was dramatically decreased in ITP patients. IL-10 treatment enhanced the suppression effect of Tregs toward Teffs, whereas anti-IL-10 treatment boosted the proliferation of Teffs and Th17 cells. Excessive activated Teffs and impaired Tregs play major roles in the exuberant CD4(+) T cells immune responses of ITP. The inhibitory effect of Tregs toward Teffs is largely exerted by IL-10. Insufficient secretion of IL-10 compromises the inhibitory capability of Tregs against Teffs in newly diagnosed ITP patients.