ABSTRACT
Objective To stimulate the expansion of natural killer cells (NK) in vivo, to achieve high expression of Flt-3 ligand ( FL) in the mouse liver by hydrodynamic injection technology , to obtain high purity of NK for cell therapy and then to purify the spleen lymphocytes by MicroBeads sorting ( MACS ) technique.Methods C57BL/6 mice were repeatedly treated with hydrodynamic injection of FL expression plasmid .Then, surface markers of splenic NK were analyzed by flow cytometry and purified by MACS technique .Results Compared with mice treated with one hydrodynamic injection, the spleen of mice treated with two hydrodynamic injections showed significant variation, with the absolute num-ber of lymphocytes increased (6.02 ±1.15) times, the proportion of NK subsets increased (2.07 ±0.39) times, and the absolute number of NK subsets increased (12.49 ±2.39) times.Cell surface marker detection confirmed that NK activity and surface markers did not change significantly .NK with a purity of about (83.81 ±0.92)％ was obtained by the combination of two magnetic beads sorted with CD 5 ( Ly-1) MicroBeads Positive selection and EasySep TM Mouse NK Cell Isolation Kit negative selection .Conclusion NK can be expanded in the spleen of mice by hydrodynamic injection of FL plasmid without influence on the NK activity and surface markers.The combined use of CD5 (Ly-1) MicroBeads positive selection with EasySep TM Mouse NK Cell Isolation Kit negative selection can effectively remove T , B and other miscellaneous cells, thereby contributing to obtaining high-purity NK. This study provides good reference for the immunotherapy of tumor cells.