目的　对 189例不同治疗阶段和 31例初治白血病患儿外周血标本进行了研究 ,以探讨小儿ALL经大剂量化疗后免疫重建的机制。方法　分别用流式细胞术间接免疫荧光法和高敏感双抗体夹心法对儿童白血病细胞表面标志和细胞因子表达水平进行检测。结果　用药后不同阶段的T辅助细胞亚群CD4均较对照组明显降低 (P <0 .0 0 0 1)。T杀伤 /抑制亚群CD8在用药初期较对照组明显增高 ,停药几年后才恢复到正常水平 (P <0 .0 0 0 1)。CD4/CD8明显倒置 (P <0 .0 0 0 1)。B细胞早期标志CD19在用药初无明显变化 ,停药后反而呈升高趋势 (P =0 .0 0 0 9)。T细胞的另一亚群之一Tα/ β在用药后也呈上升趋势 (P =0 .0 186 )。而白血病患儿用药前后NK细胞却无明显变化 (P =0 .2 846 )。与对照组相比 ,白血病患儿不同治疗阶段外周血细胞因子表达水平的差异有显著性。在白血病发病初期 ,IL 2、IL 3、IL 12、TNF α和IFN γ均显著降低。IL 2、IL 3用药期间其表达水平最低 (P <0 .0 1) ,随病情的进展呈规律变化趋势 ,停药 2～ 3年后才达正常水平。IL 4、IL 10在初治阶段表达较高 (P值分别小于 0 .0 0 1、0 .0 1) ;而在整个病情进展期间其表达却维持在较低水平。IL 6在白血病初治阶段表达水平较高 (P <0 .0 0 1)。IL 12和IFN γ在用药? OBJECTIVE: To investigate the mechanism of immune reconstitution in children with ALL after high-dose chemotherapy in 189 cases of different treatment stages and 31 cases of untreated leukemia in children. Methods Flow cytometry indirect immunofluorescence and high sensitive double antibody sandwich method were used to detect the surface markers of leukemia cells and the expression of cytokines in children. Results T helper cell subsets at different stages after treatment were significantly lower than those in the control group (P <0.01). T killer / inhibitory subpopulation CD8 was significantly higher than that of the control group in the initial period of drug treatment, and returned to the normal level after a few years’ withdrawal (P <0.0100). CD4 / CD8 was significantly inverted (P <0.0001). CD19, an early marker of B cells, showed no obvious change at the beginning of treatment, but increased gradually after stopping treatment (P = 0.090). Tα / β, one of the other subpopulations of T cells, also showed an upward trend after treatment (P = .0 186). However, there was no significant change in NK cells in children with leukemia before and after treatment (P = 0.2846). Compared with the control group, leukemia children at different stages of treatment of peripheral blood cytokine levels were significantly different. IL 2, IL 3, IL 12, TNF α and IFN γ were significantly decreased in the early stage of leukemia. IL 2, IL 3 during the period of its expression was the lowest (P <0.01), with the progression of the disease showed a trend of regular change, stopping 2-3 years after the normal level. The expression of IL-4 and IL-10 were higher in the untreated stage (P values ​​were less than 0.010 and 0.01, respectively). However, the expression of IL-4 and IL-10 remained relatively low throughout the progression of the disease. The level of IL-6 in the early stage of leukemia was higher (P <0.01). IL 12 and IFN γ in the medication?