IL-15对儿童MDS造血前体细胞bcl-2、bcl-xl mRNA表达的影响

The effect of interleukin-15 on bcl-2、bcl-xl mRNA expression of the myelodysplastic hemato-poietic cells

目的探讨IL-15对骨髓增生异常综合征(MDS)造血细胞bcl-2、bcl-xlmRNA表达的影响,以探索IL-15抑制MDSCD34造血干／祖细胞凋亡的可能机制。方法采用吸附单克隆抗体的免疫磁珠分离系统,分离纯化17例MDS患儿骨髓CD34细胞,采用RT-PCR检测bcl-2、bcl-xlmRNA表达水平,观察IL-15对它们的影响。结果IL-15可呈时间与剂量依赖性的增强体外培养的MDS造血前体细胞bcl-2、bcl-xl基因mRNA的表达。结论IL-15可能为抑制MDSCD34造血干／祖细胞凋亡的作用机制之一。

Objective Myelodysplastic syndrome(MDS) is a group of hematologic disorders characterized by a clonal abnormality of hematopoietic stem cells. The etiology of the disease remains obscure, but it may well arise as a result of the excessive apoptosis of intramedullary milieu. Many data has suggested a role of Interleukin(IL-15) as an anti-apoptotic properties in in-vitro hemtopoietic precursors in MDS patients, which might be the results of enhanced ability of bcl-2 and bcl-xl gene expression. Apart from this, IL-15 is an important bone marrow growth regulated protein. The aim of this study was to investigate the effects of IL-15 on bcl-2 and bcl-xl mRNA expression of hematopoietic cells in patients with MDS. Methods CD34+ cells in bone marrow tissue were studied from 17 MDS patients( 10 male, 4 female; age range: 1-14 years) without history of any cytokine, hormone or chemical drugs use from our hospital. According to the new WHO classification, cells were purified with an immunomagnetic beads sorting system.Cells were inoculated according to different IL-15 concentrations, i.e.0 ng/ml, 10 ng/ml, 50 ng/ml, 100 ng/ml, 200 ng/ml, respectively. Three repeats were taken for each concentration. Cells were collected at the first day and 12th day. Cells were dyed with trypan blue and counted, and then the survival rate was calculated. RT-PCR is used to detect the expression levels of bcl-2 and bcl-xl mRNA, and the effect induced by interleukin-15 was monitored in order todiscuss the possible mechanisms of IL-15 in suppressing apoptosis of hemtopoietic precursors. Results IL-15 could enhance bcl-2 and bcl-xl mRNA level of hemtopoietic cells in MDS in a dose-and time-dependent manner. The mRNA expressions were by IL-15 in a dose-related manner between the range of 0-100 ng/ml. In contrast, the mRNA expression declined at 200 ng/ml. From the first day to the eighth day, the up-regulating ability grew stronger as the action of IL-15 prolonged. However, at the 12th day, the expression of mRNA declined at 200 ng/ ml.This phenomeona might relate to the saturation of the receptor. Conclusions The effects of IL-15 may play a role in suppressing apoptosis of hemtopoietic precursors.