Circulating CD4+CD25+ Regulatory T Cell and Th3 Cell of the Patients with Myelodysplastic Syndromes.

Objective To investigate the quantitive and qualitive changes of peripheral blood CD4+CD25+ regulatory T cells and Th3 cells of the patients with myelodysplastic syndromes.

Methods Whole peripheral blood samples of 40 MDS cases and 19 nromal control were assayed by flow cytometer for detecting the numbers of CD4+CD25+ regulatory T cell and CD3+CD4+TGFβ+ T cell(Th3). Expression of FOXP3 and TGF-β of peripheral blood mononuclear cell(PBMNC) were analysed by reverse transcriptase-polymerase chain reaction(RT-PCR). Commercial ELISA kits were used to measure plasma concentrations of TGF-β 1 according to the manufacturer’s instructions.

Results. The percentage and number of CD4+CD25+ regulatory T cells in the CD4+T cell population were significantly higher in the peripheral blood of MDS patients than healthy controls[(21.5±2.2% vs 8.3±1.9%; P<0.05) and (76.1±20.6)×10⁶/L vs (54.6±11.4)×10⁶/L; P<0.05)]. The percentage and number of Th3 cells in the mononuclear cell population were significantly higher in the peripheral blood of MDS patients than healthy controls[(7.2±1.3%vs2.6±0.7%; P<0.01 and (63.5±15.2)×10⁶/L vs (42.4±10.6)×10⁶/L;P<0.05)]. The rate of expression of FOXP3 isolated from PBMNC was significantly higher in MDS patients than that in healthy controls (91.3% vs 52.6%; P<0.05%). But the expression of TGF-β of MDS patients didn’t significantly differ from that of healthy controls. The plasma level of TGF-β1 of MDS patients was significantly lower than that of healthy controls[(12.9±3.1)ng/ml vs (23.2±3.9)ng/ml; P<0.05)].

Conclusion The CD4+CD25 + regulatory T cells, Th3 cells and their inhibitive function increased in MDS, which might contribute to MDS clone escaping from immunosurveillance and gainning immunol privilege.