On the other hand , there is substanial evidences tha dcs mediate tolerane . the gm - csf - stbolated mouse bone mwderived mhc class ii + dc progendors tha are deficient in cell surface erpression of the costbolatory molecules b7 - l and b7 - 2 can induce alloanginspecific t ceil anergy in vbo . systendc adchstraion of these donor - derived dc progendors to recipients intravenously 7 days before transplantation prolonged the median graft survival tane from 9 . 5 days to 22 days wbout additional twnosuppressions in a mouse cardinc twlanation model 1995年， lul等报道表面缺乏共刺激分子，特别是缺乏cd80 ( b7 - 1 )和cd86 ( b7 - 2 )的未成熟型dc能在体外诱导同种抗原特异性的t细胞无能，而对dc的适当处理能够使未成熟型dc潜在的耐受原性得以放大和增强，使得dc在诱导免疫耐受中具有相当重要的作用及潜在的应用价值。
2.
T cell will be apopotosis , clone depletion and / or anergy , in turn inducing an antigen - specific tolerance . ctla4 ( cytotoxic t lymphocyte associated antigen 4 ) , a prominent negative costimulator , can competitively bind with b7 , and block b7 - cd28 pathway and t cell activation by producing inhibitory singals Ctla4 ( cytotoxictlymphocyteassociatedantigen4 )作为一种主要的共刺激负调节剂，可竞争性结合b7分子，阻断b7 - cd28途径、并通过产生抑制性信号使t细胞活化障碍。
3.
Transplantation has been developed to an effctive strategy for treatment of end stage diseases of multiple organs since 1950 ' s . despite success of current immunosuppressive drugs , transplantation immunologists and surgeons are still seeking to achieve tolerance to allograft . there are several different mechanisms such as clonal deletion , anergy , neglect , immuno regulation . which maintain tolerance to self - antigen . some strategies , derived from these mechanisms has been proved to be encouraged in suppression of allograft rejection 二十世纪五十年代以来，器官移植的进展使同种异体器官移植成为治疗多种器官终末期疾病的有效手段。尽管目前免疫抑制方案非常有效，但免疫耐受仍是移植免疫学家和外科医生关注的课题。有多个机制使免疫系统对自身抗原保持耐受，如：克隆清除、忽略、失能、免疫调节。
