Objective: To investigate the change of CD4⁺CD25(high)CD127(low) regulatory T cells (Tregs) percentage in patients with primary immune thrombocytopenia (ITP) treated by different methods.
Methods: One hundred and thirty-eight newly diagnosed adult ITP patients (57 male, median age 40 years, range 18-70 years) were enrolled in this study, who were randomly separated into three regiment groups, namely prednisolone (PSL, 1.5 mg/kg for 2-4 weeks and subsequently stepwise reduction) group enrolled 49 patients, dexamethasone [(one course of high-dose dexamethasone (HDD) 40 mg/day, d1-4] 45 patients, and rituximab plus HDD (rituximab 100 mg on days 7, 14, 21, 28 and HDD) group 44 patients. Peripheral blood was taken in ITP patients of each group before treatment, 14 d and 28 d after treatment. The percentages of CD4⁺CD25(high)CD127(low) Tregs in 30 healthy controls and 138 patients were analyzed by flow cytometry.
Results: Overall response (OR) rates of PSL, HDD and R+HDD groups at day 28 were 69.4%, 66.7% and 79.5% respectively with no difference. After the following 12 months, sustained response (SR) was more pronounced in R+HDD group compared to the other two groups (R+HDD vs PSL: 66.7% vs 37.8%, P<0.05; R+HDD vs HDD: 66.7% vs 22.7%, P<0.05). The percentage of CD4⁺CD25(high)CD127(low) Tregs in peripheral blood of ITP patients [(1.67±0.70)%] was significantly lower than in healthy control group; After treatment, the percentages of Tregs in peripheral blood of patients both at day 14 and 28 in R+HDD group remarkably decreased compared with before treatment [(4.28±1.09)% vs (1.68±0.68)%, P<0.05; (4.44±0.63)% vs (1.68±0.68)%]. The percentages of Tregs at day 14 in both other two groups decreased notably compared with before treatment. But the Tregs levels measured at day 28 in PSL and HDD groups were similar with before treatment.
Conclusion: The percentage of CD4⁺CD25(high)CD127(low) Tregs in peripheral blood of ITP patients was lower than healthy individual. The higher SR of patients treated by R+HDD was related to its ability to up-regulate the percentage of CD4⁺CD25(high)CD127(low) Tregs.