[Alterations of CD4+ CD25+ regulatory T cells in patients with idiopathic thrombocytopenic purpura].

OBJECTIVE: To investigate the role of CD4+ CD25+ regulatory T (Treg) cells in patients with ITP. METHODS: Flow cytometry was used to examine the number of CD4+ CD25+, CD4+ CD25 high, CD4+ Foxp3+ and CD4+ CD25+ Foxp3+ T cells. The level of Foxp3 mRNA expression was analyzed by realtime quantitative reverse transcriptase polymerase chain reaction (RT-PCR) . CD4+ CD25 high T cells was cocultured with CD4+ CD25 - T cells from patients or controls for assessing the regulatory properties of CD4+ CD25 Treg cells. RESULTS: The proportion of CD4+ CD25+ T cells in the peripheral blood of patients with ITP [(15.64 +/- 5.82) %] was significantly higher than that in normal control group [(9.30 +/- 3.95)%] (P <0.01). There was no significant difference in the percentages of CD4+ CD25 high T cells between ITP patients and controls [(1.53 +/- 0.66)% versus (1.36 +/- 0.55)% (P = 0.317)]. But the number of CD4 Foxp 3+ T cells and CD4 + CD25+ Foxp3+ T cells in patients were significantly lower than that in control group (P <0.01). The expression of Foxp3 mRNA reduced (P < 0.01) and the suppressive activity of CD4+ CD25 high T cells is lower than that of healthy controls (P <0.01). CONCLUSION: In patients with ITP, both the number and immuno-regulative function of CD4+ CD25+ Treg cells are reduced.