Critical role of neutrophil alkaline phosphatase in the antimicrobial function of neutrophils.

AIMS:To investigate the roles of neutrophil alkaline phosphatase (NAP) in the migration, reactive oxygen species (ROS) generation and apoptosis of neutrophils. MAIN METHODS:NAP was overexpressed in neutrophil-like differentiated HL-60 cells via transfecting coding sequence of NAP by lentivirus. NAP overexpression in HL-60 cells was confirmed by the methods of quantitative RT-PCR and Western blotting. HL-60 cells were induced to differentiate into neutrophil-like cells by exposure to 1.5% dimethylsulfoxide (DMSO). The migration of neutrophil-like cells were detected by Transwell migration assay. ROS generation of neutrophil-like cells were determined by flow cytometry. Neutrophil-like cells continued to be cultured for 24h, and were then harvested for apoptosis and Western blotting. KEY FINDING:After GFP-NAP infection by lentivirus, the expression of NAP was up-regulated in HL-60 cells. HL-60 cells were allowed to differentiate into neutrophil-like cells after 5-day exposure to 1.5% DMSO. Overexpression of NAP in neutrophil-like cells resulted in an increase in the number of migrated cells, intracellular ROS and cell apoptosis followed by a rise in the expression of Caspase 3, Caspase 9 and Bax, while those results were reversed in the NEG and CON group. SIGNIFICANCE:NAP might play a critical role in the anti-microbial function of neutrophils by promoting its migration and ROS generation, as well as accelerating apoptosis in neutrophils.