Introduction of shRNAs into primary NK cells with lentivirus.

Natural killer (NK) cells are lymphocytes that provide an important line of defense against viruses and tumors. Technical hurdles in genetic modifications of primary NK cell ex vivo had limited our studies of protein function(s) in NK cell differentiation, acquisition of self-tolerance, and induction of anti-tumor responses. We used VSV-G-pseudotyped, EGFP-expressing lentiviral vectors to develop an efficient gene transfer system to modify gene expression in primary murine NK cells with or without prior IL-2 activation. Lentiviral vector transduction did not impair NK cellular viability, phenotype, or functions. We also demonstrated the use of this system in modifying differentiating NK cells derived from lentiviral-transduced murine hematopoietic progenitor cells. Furthermore, the same transduction protocol is amendable to delivery of short-hairpin RNA (shRNA) for specific gene silencing. Collectively, our approach in genetic engineering of primary murine NK cells will prove useful in studying basic NK cell biology and in exploring therapeutic potentials of NK cells in inbred and transgenic mouse models.