Abstract: Objective To construct recombinant lentiviral LV5-NE and screen NB4/LV5-NE cell line. Explore the effects of neutrophil elastase on proliferation and apoptosis in NB4 cell. Method Calculate the title of LV5-NE by fluorescence counting. There were three groups (blank control group, LV5-NC group, LV5-NE), the expression level of Western blot was used to detect the expression level of NE protein and its cleaved products in NB4 cell after infected by LV5-NE. CCK-8 was used for cell proliferation analysis. Flow cytometry was used for cell cycle and apoptosis analysis. Western blot was used to detect the expression level of phosphorylated Akt, Akt ，Bax and Bcl2 in NB4 cell. Results It，s success to construct lentivir of LV5-NE and screen NB4/LV5-NE cells. Neutrophil elastase obviously promotes proliferation and inhibits apoptosis in NB4 cell（P<0.05）. Conclusion Neutrophil elastase may active PI3K/Akt pathway to promote proliferation and inhibit apoptosis in NB4 cell.

Key words: [Key words] Neutrophil elastase, lentivirus construction, proliferation, apoptosis, NB4 cell