Zhao Hong-Xia, Guo Mei, Liu Tie-Qiang, Ai Hui-Sheng
Department of Hematology, Affiliated hospital, Academy of Military Medical Sciences, Beijing 100071, China.
Zhongguo Shi Yan Xue Ye Xue Za Zhi. 2011 Jun;19(3):809-13.
This study was purposed to investigate the effect of G-CSF on the proliferation, differentiation, and cell cycle distribution of thymocytes in sublethally irradiated mice. Female BALB/c mice were exposed to 6.0 Gy γ-ray irradiation and then randomly divided into control and G-CSF treatment group. In the treatment group rhG-CSF 100 µg/(kg·d) was given subcutaneously for 14 continuous days and to make sure the first injection was given within 1 hour after irradiation. Cell cycle distribution and apoptosis of thymocytes were detected within 72 hours after irradiation. Subpopulations of CD4(-)CD8(-) cells and sequential changes in the distribution of CD4(+)CD8(+), CD8(+)CD4(-), CD8(-)CD4(+) cells were detected by a three-color flow cytometry during a four-weeks period after irradiation. The results showed that in G-CSF treatment group marked increase of cells in G(0)/G(1) phase (G-CSF vs control: 82.0 ± 5.0% vs 75.9 ± 2.8%) (p < 0.05) and a decrease of cells in S phase (G-CSF vs control: 10.2 ± 4.8% vs 15.7 ± 2.3%) (p < 0.05)could be observed as early as 6 hours after irradiation, but G-CSF seems have no evident effects on the cells in G(2)/M phase. G-CSF could also protect thymocytes against apoptosis. 6 and 12 hours after irradiation the apoptosis rates of thymic cells in G-CSF treatment group were 11.5 ± 2.4% and 15.5 ± 3.3% respectively, while in the control group the apoptosis rates were 16.5 ± 2.2% and 22.6 ± 0.7% respectively. Comparison between the two group demonstrated significant difference (p < 0.05). CD4(-)CD8(-) double negative thymocytes (DN)can be defined as DN1-4 according to their maturation. G-CSF treatment resulted in a significant increase in DN1 thymocytes and promoted their proliferation and differentiation to a more mature DN3 and DN4 stage. G-CSF could enhance the recovery of CD4(+)CD8(+) thymocytes and mitigate their relapse during reconstitution. The percentage of CD4(+)CD8(+) thymocytes in the G-CSF treatment group 28 days after irradiation was significantly higher than that of the control group (71.0 ± 6.3% vs 25.5 ± 6.3%) (p < 0.05). It is concluded that G-CSF has a positive effects on the thymic cell cycle distribution, proliferation and differentiation, which may contribute to the reconstitution of central immune system after acute irradiation.
本研究旨在探讨粒细胞集落刺激因子（G-CSF）对亚致死剂量照射小鼠胸腺细胞增殖、分化及细胞周期分布的影响。雌性BALB/c小鼠接受6.0 Gy γ射线照射，然后随机分为对照组和G-CSF治疗组。治疗组皮下注射重组人粒细胞集落刺激因子（rhG-CSF）100 μg/(kg·d)，连续14天，确保首次注射在照射后1小时内进行。照射后72小时内检测胸腺细胞的细胞周期分布和凋亡情况。照射后4周内，采用三色流式细胞术检测CD4(-)CD8(-)细胞亚群以及CD4(+)CD8(+)、CD8(+)CD4(-)、CD8(-)CD4(+)细胞分布的动态变化。结果显示，在G-CSF治疗组，照射后6小时即可观察到G(0)/G(1)期细胞显著增多（G-CSF组与对照组：82.0 ± 5.0% 比 75.9 ± 2.8%）（p < 0.05），S期细胞减少（G-CSF组与对照组：10.2 ± 4.8% 比 15.7 ± 2.3%）（p < 0.05），但G-CSF对G(2)/M期细胞似乎无明显影响。G-CSF还可保护胸腺细胞免受凋亡。照射后6小时和12小时，G-CSF治疗组胸腺细胞的凋亡率分别为11.5 ± 2.4%和15.5 ± 3.3%，而对照组的凋亡率分别为16.5 ± 2.2%和22.6 ± 0.7%。两组比较差异有统计学意义（p < 0.05）。CD4(-)CD8(-)双阴性胸腺细胞（DN）可根据其成熟程度分为DN1-4。G-CSF治疗使DN1胸腺细胞显著增多，并促进其增殖和分化至更成熟的DN3和DN4阶段。G-CSF可促进CD4(+)CD8(+)胸腺细胞的恢复，并减轻其在重建过程中的复发。照射后28天，G-CSF治疗组CD4(+)CD8(+)胸腺细胞的百分比显著高于对照组（71.0 ± 6.3% 比 25.5 ± 6.3%）（p < 0.05）。结论：G-CSF对胸腺细胞周期分布、增殖和分化具有积极作用，可能有助于急性照射后中枢免疫系统的重建。
