HepG2细胞抗原对脐血CD34^＋造血干细胞诱导分化的树突细胞免疫功能的影响

背景：树突细胞（DC）是体内功能最强的抗原呈递细胞，可激活初始型T细胞，生成辅助性T细胞和杀伤性T细胞。DC具有特异性呈递肿瘤抗原的能力，在肿瘤免疫中发挥重要作用。目的：探讨HepG2细胞抗原对脐血CD34^＋造血干细胞诱导分化的DC免疫功能的影响。方法：分离培养脐血CD34^＋造血干细胞后，加入细胞因子组合诱导生成DC并将其分成HepG2细胞抗原负载组和对照组．以流式细胞仪测定DC生成率和免疫表型，以酶联免疫吸附测定（ELISA）检测干扰素-γ（IFN-γ）含量，以MTT法检测细胞毒性T淋巴细胞（CTL细胞）对HepG2细胞的杀伤作用。结果：DC生成率为60．2％±9．4％。与对照组相比，HepG2细胞抗原负载组DC免疫表型CD1a^＋／CD40^＋、CD83^＋／CD86^＋、CD14^＋／HLA-DR^＋比例显著增高（57．6％±5．4％对33．2％±6．0％、32．5％±3．9％对26．0％±2．8％、38．1％±2．6％对29．1％±2．1％，P〈0．01）；IFN-γ含量呈时间依赖性增高；CTL细胞对HepG2细胞的杀伤作用显著增强（43.3％±11.3％对13．9％±4．6％，P〈0．01）。结论：应用HepG2细胞抗原孵育脐血CD34^＋造血干细胞可诱导分化成熟DC，DC可促进异基因淋巴细胞活化分泌IFN-γ，并产生特异性CTL细胞，杀伤肝癌HepG2细胞。

Effect of HepG2 Cell Antigen on Immune Function of Dendritic Cells Induced and Differentiated From CD34+ Hematopoietic Stem Cells in Cord Blood

Background： Dendritic cells （DC） are the strongest cells possessing the function of antigen presenting cell in body. DC can activate naive T cells to generate helper T cells and killer T cells. DC can present tumor antigen specifically and play important roles in tumor immunity. Aims： To investigate the effect of HepG2 cell antigen on immune function of DC induced and differentiated from CD34^＋ hematopoietic stern cells in cord blood. Methods： CD34^＋ hematopoietic stem cells in cord blood were separated and cultured, DC were induced with combined cytokines and then were divided into HepG2 cell antigen-pulsed group and control group. Levels and phenotypes of DC were measured by flow cytometry. Level of interferon （IFN）-γ was determined by enzyme-linked immunosorbent assay （ELISA）. Lethal effect of cytotoxic T lymphocyte （CTL） cells on HepG2 cells was measured by MTT method. Results： The generation rate of DC was 60.2%±9.4%. Compared with control group, the proportions of CD1a^＋/CD40^＋, CD83^＋/CD86^＋ and CD14^＋/HLA-DR^＋ in HepG2 cell antigen-pulsed group were significantly increased （57.6%±5.4% vs. 33.2%±6.0%, 32.5%±3.9% vs. 26.0%±2.8% and 38.1%±2.6% vs. 29.1%±2.1%, respectively, P〈0.01）. The IFN-γcontent was significantly increased in a time-dependent manner in HepG2 cell antigenpulsed group. The killing rate of CTL cells on HepG2 cells was significantly increased （43.3%±11.3% vs. 13.9%±4.6%, P〈 0.01）. Conclusions： HepG2 cell antigen can promote the immune function of DC induced and differentiated from CD34^＋ hematopoietic stem cells in cord blood, and DC can activate heterogen lymphocyte to secret IFN-γ and induce specific CTL cells to kill HepG2 cells.