摘要In this study,norcanthridin(NCTD)-encapsulated liposomes were modified with a novel murine anti-human CD19 monoclonal antibody 2E8(2E8-NCTD-liposomes)and the targeting efficiency and specific cytotoxicity of 2E8-NCTD-liposomes to CD19+leukemia cells were evaluated.BALB/c mice were injected with 2E8 hybridoma cells to obtain 2E8 monoclonal antibody(mAb).NCTD-liposomes were prepared by using film dispersion method.2E8 mAbs were linked to NCTD-liposomes using post-incorporation technology.Flow cytometry showed that the targeting efficiency of purified 2E8 mAbs on CDI9+Nalm-6 cells was 99.93%.The purified 2E8 mAbs were conjugated with NCTD-liposomes to prepare 2E8-NCTD-liposomes whose targeting efficiency on CD19+Nalm-6 was also 95.82%.The average size of 2E8-NCTD-liposomes was 118.32 nm in diameter.HPLC showed that the encapsulation efficiency of NCTD was 46.51%.When the molar ratio of 2E8/MaI-PEG2000-DSPE reached 1:50,we obtained the liposomes with 9 2E8 molecules per liposome.The targeting efficiency of 2E8-NCTD-liposomes on CD19+leukemia cells was significantly higher than that on CD19-leukemia cells.Similarly,the targeting efficiency of the immunoliposomes was also higher than that of the NCTD-liposomes on CD 19+leukemia cells.Those results were consistent with those observed by laser scanning confocal microscopy.3-(4,5-Dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide(MTT)assay demonstrated that 2E8-NCTD-liposomes specifically killed Nalm-6 cells in a dose-and time-dependent manner.The viability of Nalm-6 cells treated by 2E8-NCTD-liposomes was significantly lower than that of Molt-3cells and it was also significantly lower than that of Nalm-6 cells treated with the same concentration of NCTD-liposomes or free NCTD.We are led to concluded that 2E8 antigen can serve as a specific targeting molecule of B lineage hematopoietic malignancies for liposome targeting,and 2E8-NCTD-liposomes can be used as a new and effective means for the treatment of B lineage hematopoietic malignancies.