Experimental Study On The Role Of CD4～+CD25～+ Regulatory T Cell In Inmunosupression Of Leukemia Animal Models

Objectives:To explore the role of CD4⁺CD25⁺ regulatory T cells in leukemia Immunosuppression by testing the percentage of T cell subsets and the expression of Foxp3 mRNA in leukemia mice models in order to provide experimental evidence for clinical diagnosis and therapy of the leukemia.Methods:We have inoculated the C57BL/6 mice with the erithroleukemic cell line FBL₃ and established leukemia mice models.The CD4⁺CD25⁺ subset in the spleen,peripheral blood and tumor tissues of 10 leukemia-beared mice were analyzed by the FCM,the expression of Foxp3 mRNA in the spleen and tumor tissues of 10 leukemia-beared mice were measured by RT-PCR.The normal 10 mice which were not transplanted leukemic cell were used for control.Results:â‘ There were no significant differences in the percentage of CD4⁺CD25⁺ regulatory T cells in the peripheral blood and spleen of normal mice(4.48±0.63%,3.80±1.07 %,P＞0.05);The proportion of CD4⁺CD25⁺/CD4⁺ T cell in the spleen of normal mice was significantly higher than that in the peripheral blood of normal mice(20.23±2.07%;14.01±0.86 %,P＜0.001).â‘¡The percentage of CD4⁺CD25⁺ regulatory T cells in the spleen of leukemia-beared mice was significantly higher than that of the control(16.2±0.56%;3.80±1.07 %,P＜0.001).There were no obvious differences in the percentage of CD4⁺CD25⁺ regulatory T cells in the peripheral blood between leukemia-beared mice and normal mice(4.51±0.41%; 4.48±0.63%,P＞0.05).The percentage of CD4⁺CD25⁺ regulatory T cells in tumor tissues was very lower than that in the spleen and peripheral blood(1.31±0.11%,P＜0.01).â‘¢The results measured by RT-PCR showed that the expression of Foxp3 in the spleen of leukemi-beared mice was significantly higher than that of the control(1.13±0.25;0.54±0.12,P＜0.01),the expression of Foxp3 in tumor tissues was significantly lower than that in the spleen and peripheral blood of leukemia-beared mice(0.35±0.07,P＜0.01).Conclusions:â‘ No significant difference was observed in the distribution of CD4⁺CD25⁺ Treg cells between the peripheral blood and spleen in normal mice.â‘¡The distribution of CD4⁺CD25⁺ subset in spleen of leukamia-bearing mice was significantly higher than that in the peripheral blood.It revealed that the downregulation of antitumor immunity may be closely related to CD4⁺CD25⁺ subset.â‘¢The results measured by RT-PCR showed that the expression of Foxp3 in the spleen of leukemi-beared mice was significantly higher than that of the control, that was consistented with the the percentages of CD4⁺CD25⁺ subset by FCM.