Anti-West Nile virus activity of in vitro expanded human primary natural killer cells

BMC Immunol. 2010 Jan 20;11:3. doi: 10.1186/1471-2172-11-3.


Background: Natural Killer (NK) cells are a crucial component of the host innate immune system with anti-viral and anti-cancer properties. However, the role of NK cells in West Nile virus (WNV) infection is controversial, with reported effects ranging from active suppression of virus to no effect at all. It was previously shown that K562-mb15-41BBL (K562D2) cells, which express IL-15 and 4-1BBL on the K562 cell surface, were able to expand and activate human primary NK cells of normal peripheral blood mononuclear cells (PBMC). The expanded NK cells were tested for their ability to inhibit WNV infection in vitro.

Results: Co-culture of PBMC with irradiated K562D2 cells expanded the NK cell number by 2-3 logs in 2-3 weeks, with more than 90% purity; upregulated NK cell surface activation receptors; downregulated inhibitory receptors; and boosted interferon gamma (IFN-gamma) production by approximately 33 fold. The expanded NK (D2NK) cell has strong natural killing activity against both K562 and Vero cells, and killed the WNV infected Vero cells through antibody-dependent cellular cytotoxicity (ADCC). The D2NK cell culture supernatants inhibited both WNV replication and WNV induced cytopathic effect (CPE) in Vero cells when added before or after infection. Anti-IFN-gamma neutralizing antibody blocked the NK supernatant-mediated anti-WNV effect, demonstrating a noncytolytic activity mediated through IFN-gamma.

Conclusions: Co-culture of PBMC with K562D2 stimulatory cells is an efficient technique to prepare large quantities of pure and active NK cells, and these expanded NK cells inhibited WNV infection of Vero cells through both cytolytic and noncytolytic activities, which may imply a potential role of NK cells in combating WNV infection.

MeSH terms

  • Antibodies, Blocking / pharmacology
  • Cell Culture Techniques
  • Cell Proliferation
  • Coculture Techniques
  • Cytopathogenic Effect, Viral / drug effects
  • Cytopathogenic Effect, Viral / immunology
  • Cytotoxicity, Immunologic / drug effects
  • Humans
  • Interferon-gamma / biosynthesis
  • Interferon-gamma / genetics
  • Interferon-gamma / immunology*
  • Interferon-gamma / pharmacology
  • K562 Cells
  • Killer Cells, Natural / drug effects
  • Killer Cells, Natural / immunology
  • Killer Cells, Natural / metabolism*
  • Killer Cells, Natural / pathology
  • Lymphocyte Activation*
  • Receptors, Natural Killer Cell / metabolism
  • Virus Replication / drug effects
  • Virus Replication / immunology
  • West Nile Fever / immunology*
  • West Nile Fever / virology
  • West Nile virus / pathogenicity
  • West Nile virus / physiology*


  • Antibodies, Blocking
  • Receptors, Natural Killer Cell
  • Interferon-gamma