[Expression of CD4+ CD25+ regulatory T cells in the patients with acute lymphocytic leukemia]

To evaluate the proportion of CD4(+) CD25(+) Tregs in the peripheral blood of the patients suffering from acute lymphocytic leukemia (ALL) with or without chemotherapy and investigate whether the serum from patients could convert peripheral CD4(+) CD25(-) T cells to CD4(+) CD25(+) Tregs.

The proportion of CD4(+) CD25(+) T cells in the peripheral blood of three groups of people (the patients with ALL before therapy, the patients with ALL who achieved partial remission (PR) or complete remission (CR) and the healthy donors) was evaluated by flow cytometry. The level of Foxp3 mRNA expression of each group was examined by FQ-RT-PCR. Furthermore mononuclear cells isolated from the peripheral blood of the healthy donors were added to laboratory serum of ALL and control serum of healthy donors respectively. Each group was divided into sub-groups according to various serum doses. After culture for 72 h, the cells of all the groups were harvested separately and further tested for the expression of CD4(+) CD25(+) T cells by flow cytometry. The FQ-RT-PCR method was used to examine the expression of Foxp3 mRNA expression.

The percentage of CD4(+) CD25(+) T cells and Foxp3 in the patients with ALL after chemotherapy was significantly higher than that of the healthy donors and the patients with ALL without chemotherapy. Although the proportion of CD4(+) CD25(+) T cells in the patients with ALL without chemotherapy was almost the same with that in the healthy donors, the level of Foxp3 mRNA expression in the former was higher. Moreover, the proportion of CD4(+) CD25(+) T cells and the level of Foxp3 mRNA expression in experimental group were statistically higher than those in control group. The expression of Foxp3 mRNA in control group did not vary with the serum dosage.

The proportion of CD4(+) CD25(+) Foxp3+Tregs in the peripheral blood of the patients with ALL with or without chemotherapy is significantly higher than that of healthy donors. The serum derived from the patients with ALL can convert CD4(+) CD25(-) T cells to CD4(+) CD25(+) Tregs, which might be one of the important reasons for immunosuppression in ALL.