title: Anti-West Nile virus activity of in vitro expanded human primary natural killer cells.
abstract: 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.
authors.affiliation: Laboratory of Molecular Virology, Center for Biologics Evaluation and Research, Food and Drug Administration, 1401 Rockville Pike, Rockville, MD 20892, USA. ming.zhang@fda.gov.
authors.forename: Mingjie
authors.initials: M
authors.lastname: Zhang
authors.forename: Sylvester
authors.initials: S
authors.lastname: Daniel
authors.forename: Yong
authors.initials: Y
authors.lastname: Huang
authors.forename: Caren
authors.initials: C
authors.lastname: Chancey
authors.forename: Qingsheng
authors.initials: Q
authors.lastname: Huang
authors.forename: Ying F
authors.initials: YF
authors.lastname: Lei
authors.forename: Andriyan
authors.initials: A
authors.lastname: Grinev
authors.forename: Howard
authors.initials: H
authors.lastname: Mostowski
authors.forename: Maria
authors.initials: M
authors.lastname: Rios
authors.forename: Andrew
authors.initials: A
authors.lastname: Dayton
mesh_terms: D019138:Antibodies, Blocking / Q000494:pharmacology; D018929:Cell Culture Techniques; D049109:Cell Proliferation; D018920:Coculture Techniques; D003588:Cytopathogenic Effect, Viral / Q000187:drug effects / Q000276:immunology; D003602:Cytotoxicity, Immunologic / Q000187:drug effects; D006801:Humans; D007371:Interferon-gamma / Q000096:biosynthesis / Q000235:genetics / Q000276:immunology* / Q000494:pharmacology; D020014:K562 Cells; D007694:Killer Cells, Natural / Q000187:drug effects / Q000276:immunology / Q000378:metabolism* / Q000473:pathology; D008213:Lymphocyte Activation; D055607:Receptors, Natural Killer Cell / Q000378:metabolism; D014779:Virus Replication / Q000187:drug effects / Q000276:immunology; D014901:West Nile Fever / Q000276:immunology* / Q000821:virology; D014902:West Nile virus / Q000472:pathogenicity / Q000502:physiology*
chemical_list: D019138:Antibodies, Blocking; D055607:Receptors, Natural Killer Cell; D007371:Interferon-gamma