急性髓细胞性白血病细胞培养上清对树突细胞分化、成熟、凋亡及功能的影响

背景与目的:树突细胞(dendritic cell,DC)存机体抗瘤免疫中起重要作用.研究已表明肿瘤患者和荷瘤动物体内DC功能受损并伴有DC数量的降低.最近的研究提示这种DC功能的受损可能是肿瘤细胞分泌的可溶性因子介导的免疫抑制所致.本研究拟观察急性髓系白血病(acute myeloid leukemia,AML)细胞分泌的可溶性因子对单核细胞来源DC的分化、成熟、凋亡及其功能的影响.方法:原代AML细胞培养24 h后收集上清.在含有或不含有AML细胞培养上清的培养液中,利用IL-4和GM-CSF刺激单核细胞分化成不成熟DC(immature DC,iDC),IL-1β、IL-6、TNF-α和PGE-2促进DC成熟.流式细胞仪检测DC表型和凋亡率的变化.计算前体细胞频率(precursorfrequency,PF),观察DC对异基因CD4 T细胞和CD8 T细胞的刺激功能.结果:AML细胞培养上清可显著抑制DC表面协同刺激分子CD80和CD86的表达,并可降低促成熟细胞因子对DC的促成熟作用.同时,与对照组相比,AML细胞培养上清可显著诱导DC的凋亡,凋亡率分别为(15.1±4.2)%和(29.4±9.5)%(P＜0.01).相对于正常成熟DC,AML细胞培养上清诱生的DC对异基因CD4 T细胞和CD8 T细胞的刺激功能显著降低(P＜0.01),其中CD4 T细胞的前体细胞频率分别为(5.2±1.6)%和(1.8±0.5)%,CD8 T细胞的前体细胞频率分别为(6.5±2.0)%和(2.1±0.6)%.结论:AML细胞分泌的可溶性因子可抑制DC的发育和功能.

Effects of soluble secreted by acute myeloid leukemia cells on differentiation, maturation, apoptosis, and functions of dendritic cells

BACKGROUND & OBJECTIVE: Dendritic cells (DCs) play an important role in the immunosurveillance against cancer. It has been shown that the function of DCs is impaired and their population decreases in cancer-bearing hosts. Recent observations suggest that the inability of DCs could be a result of the immunosuppression mediated by soluble factors secreted by tumor cells. This study was to investigate the effects of soluble factors secreted by acute myeloid leukemia (AML) cells on the differentiation, maturation, apoptosis, and functions of DCs derived from normal mononuclear cells. METHODS: Mononuclear cells were cultured with interleukin-4 (IL-4) and granulocyte-macrophage colony-stimulating factor (GM-CSF), in the presence or absence of 24-hour culture supernatants from fresh primary AML cells, to generate immature DCs. The maturation of DCs was induced by cytokines IL-1beta, IL-6, tumor necrosis factor-alpha (TNF-alpha), and prostaglandin-2 (PGE-2). The phenotypic and apoptotic alterations of DCs were evaluated using flow cytometry. Precursor frequency (PF) was calculated to monitor the allostimulatory effects of DCs on CD4+ and CD8+ T cells. RESULTS: AML cell supernatant-treated DCs showed significantly lower expression of co-stimulatory molecules CD80 and CD86, and reduced response to cytokines IL-1beta, IL-6, TNF-alpha, and PGE-2. The apoptosis rate was significantly lower in AML cell supernatant-treated DCs than in control DCs (29.4+/-9.5)% vs. (15.1+/-4.2)%, P<0.01]. The allostimulatory effects of AML cell supernatant-treated DCs on CD4+ and CD8+ T cells were significantly lower than those of normal mature DCs PF: (1.8+/-0.5)% vs. (5.2+/-1.6)% for CD4+ T cells, (2.1+/-0.6)% vs. (6.5+/-2.0)% for CD8+ T cells, P<0.01]. CONCLUSION: Soluble factors derived from AML cells could inhibit development and functions of DCs.