Abnormal CD25 expression on hematopoietic cells in myelodysplastic syndromes

Objective: To investigate the frequencies and biological characteristics of CD25 positive hematopoietic stem cells (HSC) in myelodysplastic syndromes. Methods: The expression of CD25 on HSC in bone marrow derived from patients with untreated MDS patients, untreated AML patients and normal controls were accessed by flow cytometry (FCM). The correlation analysis was done between CD25(+) HSC and clinical parameters in MDS patients. Results: The expression of CD25 on HSC (CD34(+) CD38-cells) in MDS patients (28.81%) was significantly higher than that in normal controls (9.41%, P=0.020), which similar to that in AML patients (32.54%, P=0.410). The CD25 expression on HSC was positively correlated with the CD123 expression on HSC (r=0.602, P=0.008). The expression of CD25 on HSC in high-risk MDS group (53.27%) based on IPSS score was significantly higher than that in low-risk MDS group (18.66%, P=0.003). In MDS patients, CD25(+) HSC were negatively correlated with the counts of neutrophils (r=-0.684, P=0.002) and platelets (r=-0.561, P=0.015), while positively correlated with the percentage of blasts in bone marrow (r=0.596, P=0.009). The CD25 expression on erythroblasts had a significant positive correlation with red blood cell counts in MDS patients (r=0.536, P=0.012). Conclusions: CD25 was over-expressed on HSC in MDS patients, especially in high-risk MDS patients. Increased CD25(+) HSC was correlated with progression of MDS. Low-expression of CD25 on erythroblasts might correlate with anemia in MDS patients. CD25 could be a specific marker of LSC in MDS, and could involve in the mechanisms of development and progression of MDS.