title: Interleukin-15 supports generation of highly potent clinical-grade natural killer cells in long-term cultures for targeting hematological malignancies.
abstract: OBJECTIVE
  Interleukin (IL)-15 is a promising novel cytokine for natural killer (NK) cell activation and survival. We studied the effects of IL-15 compared to IL-2 on NK cells in long-term cultures for clinical translation.
  
  
  METHODS
  CD56(+)CD3(-) NK cells were expanded with IL-2 or IL-15 for 2 to 4 weeks within lymphokine-activated killer (LAK) cell cultures (LAK-NK) in serum-enriched AIM V or CellGro Stem Cell Growth Medium (SCGM). Cell growth, viability, and NK cell content were monitored and cytotoxicity assessed in a flow cytometric cytotoxicity assay.
  
  
  RESULTS
  IL-15 (100-1000 U/mL) could replace IL-2 (1000 U/mL) in AIM V cultures to achieve efficient LAK cell expansion. However, IL-15-stimulated LAK cells exceeded cytotoxicity of IL-2-stimulated LAK cells against K562, notably at later culture points. In the powerful CellGro SCGM, LAK cells expanded over 28 days an average of 905-fold ± 320-fold standard error of the mean (SEM) for IL-2 (500 U/mL) and 484-fold ± 98-fold SEM for IL-15 (500 U/mL), and NK cells within such LAK cultures expanded an average of 2320-fold ± 975-fold SEM for IL-2 and 1084-fold ± 309-fold SEM for IL-15. Importantly, such IL-15-activated LAK-NK cells retained enhanced cytotoxicity at later culture points against K562 as well. IL-15-stimulated effectors were also highly cytotoxic against hematological targets MOLT-4 and KU812 and nontoxic against autologous nonmalignant cells. Interestingly, IL-15-LAK-NK cells showed overall significant upregulation of the main activating and inhibitory NK cell receptors after long-term cytokine stimulation.
  
  
  CONCLUSIONS
  Our results demonstrate the potential for IL-15 to support large-scale expansion of clinical-grade LAK-NK effectors, which could retain enhanced longer-term potency and preserve activation receptors in therapy of hematological malignancies. Protocols are readily clinically translatable.
authors.affiliation: Blood Services Group, Health Sciences Authority, Singapore. Garnet_suck@hsa.gov.sg
authors.forename: Garnet
authors.initials: G
authors.lastname: Suck
authors.forename: Vincent Y S
authors.initials: VY
authors.lastname: Oei
authors.forename: Yeh Ching
authors.initials: YC
authors.lastname: Linn
authors.forename: Seih Hwa
authors.initials: SH
authors.lastname: Ho
authors.forename: Sixian
authors.initials: S
authors.lastname: Chu
authors.forename: Alicia
authors.initials: A
authors.lastname: Choong
authors.forename: Madelaine
authors.initials: M
authors.lastname: Niam
authors.forename: Mickey B C
authors.initials: MB
authors.lastname: Koh
mesh_terms: D001769:Blood; D002460:Cell Line; D002478:Cells, Cultured; D005434:Flow Cytometry; D019337:Hematologic Neoplasms / Q000473:pathology / Q000628:therapy*; D006801:Humans; D019409:Interleukin-15 / Q000502:physiology*; D007694:Killer Cells, Natural / Q000166:cytology*
chemical_list: D019409:Interleukin-15