Dendritic cells ( dc ) is the most powerful apc , which can markedly increase the antigen - presentation capacity by maximizing the pepitide - mhc complexes on the cell surface and upregulating the co - stimulatory ligands b7 - 1 and b7 - 2 , adhesion moleculees such as il - 12 that promote full activation of lymphocytes . full activation of antigen - specific t cells requires two signals - one signal coming via the tcr and the other signal through engagment of co - stimulatary molecules . t cells receiving one signal via their tcr are turned off by mhc ( major histocompatibility complex ) , via t cell cd28 binding to b7 on the dc induce tlymphokine and t cell proliferatiion T细胞介导的细胞免疫在控制肿瘤生长方面发挥着重要作用， t细胞在发挥抗瘤效应(分泌细胞因子和直接杀伤)之前必须先经过活化，体内专职抗原提呈细胞( apc )细胞并使其活化，树突状细胞( dendriticcell , dc )为t细胞的激活提供双重信号， t细胞借助tcr识别由dcmhc分子递交的抗原肽后，通过tcr - cd3复合体传递抗原特异性识别信号(第一信号) ，以cd28为主的t细胞表面辅佐分子识别dc表面b7分子，传递非特异性协同刺激信号(第二信号) ，在机体抗肿瘤免疫应答中处于核心地位。
Dendritic cells are characterized by their ability to efficiently present antigen , and are uniquely equipped to stimulate naive t cell responses . immature dendritic cells acquire antigens from throughout the peripheral body , then migrate to t - lymphocyte - dependent areas of lymph nodes . thus , dendritic cells act as bridges , operating at the interface of innate and acquired immunity 作为机体免疫系统中功能最强的专职性抗原提呈细胞( antigen - presentingcells , apc ) ，树突状细胞( dendriticcells , dc )能高效地摄取、加工处理和提呈抗原，具有较强的迁移能力，并能显著地激活初始型t细胞以启动t细胞免疫应答反应，此外， dc与b细胞以及nk细胞等也存在着相互作用，可见， dc在连接天然免疫和获得性免疫之间起着非常重要的作用。
Dcs play a pivotal role in the development of antitumor immunity . t lymphocytes immune response induced by direct antigen - pulsed dcs can not maintain longer for peptides - mhc department or mhc molecules degeneration . the method of dcs loading with tumor antigen gene is another potential approach to enhancing and maintaining immune response 在用抗原直接刺激dc时，由于抗原- mhc复合物解离或细胞mhc分子降解而不能维持所诱导的t细胞免疫应答，借助载体把肿瘤抗原基因导入dc后肿瘤抗原在dc内的持续表达能增强其抗原提呈能力并能维持所诱导的免疫效应。
Cd 14 * monocytes or bone marrow derived hematopoietic progenitor cells cultured with granulocyte - macrophage colony - stimulating factor ( gm - csf ) and il - 4 differentiate into efficient apc with morphology and cell surface molecule expression typical of immature dc . it was demonstrated that a variety of factors ( such as lps , tnf - a , il - 1 , monocyte - conditioned medium , and cd40 receptor cross - linking ) induce the maturation of immature dc to mature dc that are much more potent in activating t cells by increasing the expression of costimulatory molecules and cytokines , promoting the migration of dc to draining lymph nodes , and down - regulating the capacity of dc to capture and process antigen 在体外，外周血cd14 ~ +单核细胞和cd34 ~ +骨髓造血前体细胞在粒细胞-巨噬细胞集落刺激因子( granulocyte - macrophagecolony - stimulatingfactor , gm - csf )和il - 4的共同作用下可分化为未成熟dc ，未成熟dc具有强大的摄取和处理抗原的能力，但其抗原提呈能力较弱；未成熟dc在炎性细胞因浙江大竿俗士学位论文潜廷平子汐ilq ， yfax病原成分汐lpsx单核细胞条件培养液或cd40l等作用下可分化为成熟dc 。
The auhors also noticed tha following injection of these iabe dc progendors , iabe cells tha also expressed b7 - l or b7 - 2 could be detected in t - dependent areas of c3h ( h2k ) recipient spleens within 7 days . tha rnay reflect the up - regulation of the costdrilatory molecu1es on these injected dc progeultors , which then shifted from " tolerogenic " to " inunnogenic " , under the complex cytokine ndlieu in vivo 本研究通过体外培养、扩增骨髓来源的dc ，分析、比较了未成熟型dc和成熟型dc的表型特征的差异，观察未成熟型和成熟型dc抗原提呈功能及介导同种混合e51g ：
To date , there are few successful cases in the immunotherapy of cancer patients . the reasons for this have been the limited availability of tumor - associated antigens ( taa ) and the inability to deliver such antigens in a manner that renders them immunogenic and activates t cell responses in patients with cancer 树突状细胞( dendriticcells ， dc )是抗原提呈细胞( antigenpresentingcells ， apc )的一个特殊群体，虽然在体内数量很少，但其分布十分广泛，是体内功能最强大的apc 。
