Objective   To evaluated the proportion of CD4⁺CD25⁺ Tregs cells in the peripheral blood of patients with chronic myelogenous leukemia (CML), and to investigate the correlation among the proportion of CD4⁺CD25⁺Tregs, curative effect, and prognosis of patients with CML at different phases. The onset and turnover of CML based on immunology were discussed.

  Methods   Flow cytometry was used to determine the proportion of CD4⁺CD25⁺ Tregs in peripheral blood from 23 CML patients and 10 normal controls. The proportion was compared among CML patients, normal controls, and different phases of the disease. The correlation between the proportion of T cells and clinical parameters was analyzed.

  Results   Compared with normal controls, the percentage of CD4 +CD25 + Tregs in the peripheral blood mononuclear cells (PBMC) was significantly lower (P < 0.05) in patients who underwent initial treatment of CML and in those with accelerated or blastic phase CML. Moreover, there were no significant differences in the percentage of CD4⁺CD25⁺ Treg cells in the PBMC of patients during treatment of CML and normal controls (P > 0.05). Percentages of CD4⁺T cells in the PBMC of patients receiving initial treatment of CML and those with accelerated or blastic phase CML was significantly lower (P < 0.05) than normal controls. There were no significant differences in CD4⁺T cell percentage in PBMC of the patients during treatment of CML and normal controls (P > 0.05). A comparison of the percentages of CD4⁺CD25⁺Treg cell in the PBMC of CML patients at various stages of the disease demonstrated an significant increase (P < 0.05) in the percentage in patients at the chronic stabilized phase compared with those in the initial treatment. No significant differences were found among the other groups (P > 0.05). There was a positive correlation between the percentage of CD4 ⁺CD25 ⁺ Treg cells in the PBMC of patients undergoing initial treatment of CML and the protein level of peripheral blood hemoglobin (P = 0.010). There was a negative correlation between PBMC of patients in initial treatment of CML and the percentage of juvenile cells in the bone marrow (progranulocyte + promyelocyte) (P = 0.022).

  Conclusion   There is abnormal expression of CD4⁺CD25⁺ Tregs in CML patients and that the percentage of cells decreases with disease progression. A decrease in CD4⁺ T cell percentage may be used as an indicator of disease progression into the accelerated or blastic phase.CD4⁺CD25⁺ Tregs levels correlate with higher hemoglobin content and lower ratio of juvenile cells (myeloblast plus promyelocyte) in the bome marrow.