ABSTRACT
<p><b>OBJECTIVE</b>To investigate the expressions of STAT5 phosphorylation in CD34(+)CD38(-)CD123(+) bone marrow cells of the patients with myelodysplastic syndromes (MDS), and then evaluate the level of activation of STAT5 associated with cell proliferation in MDS clone cells.</p><p><b>METHODS</b>The bone marrow mononuclear cells (BMMNC) were extracted from 36 MDS patients and 14 normal controls. The mean fluorescence intensities (MFI) of phosphorylated STAT5(P-STAT5) in CD34(+)CD38(-)CD123(+) and CD34(+)CD38(-)CD123(-)cells, with or without the stimulation of 10 U/ml EPO, were examined by flow cytometry (FCM).</p><p><b>RESULTS</b>Without stimulation, the P-STAT5 MFI in CD34(+)CD38(-)CD123(+) cells of low/high risk MDS patients was 113.71 ± 67.22/173.05 ± 102.78, which was significantly higher than that of CD34(+)CD38(-)CD123(-) cells (58.84 ± 27.51/68.99 ± 50.42, P < 0.01, P < 0.05) and the normal controls CD34(+)CD38(-)CD123(-) cells (63.06 ± 21.06, P < 0.05), there was no significant difference between the CD34(+)CD38(-)CD123(-) cells of MDS patients and the normal control CD34(+)CD38(-)CD123(-) cells; With the EPO stimulation, the P-STAT5 MFI in CD34(+)CD38(-)CD123(+) cells of low/high risk MDS patients was 144.04 ± 58.11/239.45 ± 152.05, which was significantly higher than that of CD34(+)CD38(-)CD123(-) cells (68.41 ± 25, 10/64.21 ± 23.43, P < 0.01) and the normal controls CD34(+)CD38(-)CD123(-) cells (75.21 ± 27.02, P < 0.01), there was no significant difference between the CD34(+)CD38(-)CD123(-) cells of MDS patients and the normal control CD34(+)CD38(-)CD123(-) cells; The P-STAT5 MFI in the CD34(+)CD38(-)CD123(+) cells of low/high risk MDS patients with or without EPO stimulation were 21.80/28.86, which was significantly higher than that of CD34(+)CD38(-)CD123(-) cells (7.42/5.50, P < 0.01, P < 0.05) and the normal controls CD34(+)CD38(-)CD123(-) cells (6.39, P < 0.05), there was no significant difference between the CD34(+)CD38(-)CD123(-) cells of MDS patients and the normal controls CD34(+)CD38(-)CD123(-) cells; There was no significant difference of P-STAT5 MFI with or without EPO stimulation and the increased P-STAT5 MFI between the CD34(+)CD38(-)CD123(+) cells of low and high risk MDS.</p><p><b>CONCLUSION</b>STAT5 associated with cell proliferation was activated in CD34(+)CD38(-)CD123(+) bone marrow cells in MDS, which had more significant reactions to EPO than CD34(+)CD38(-)CD123(-) cells, indicating that CD34(+)CD38(-)CD123(+) bone marrow cells might be the real malignant MDS clone cells in MDS.</p>