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  3. Expansion of Human NK Cells Using K562 Cells Expressing OX40 Ligand and Short Exposure to IL-21

Expansion of Human NK Cells Using K562 Cells Expressing OX40 Ligand and Short Exposure to IL-21

  • Front Immunol. 2019 Apr 24;10:879. doi: 10.3389/fimmu.2019.00879.
SoonHo Kweon 1,  Minh-Trang Thi Phan 2,  Sejong Chun 3,  HongBi Yu 4,  Jinho Kim 4,  Seokho Kim 5,  Jaemin Lee 5,  Alaa Kassim Ali 6,  Seung-Hwan Lee 6,  Sang-Ki Kim 7,  Junsang Doh 8,  Duck Cho 9 10 11
Affiliations

Affiliations

  • 1 School of Interdisciplinary Bioscience and Bioengineering (I-Bio), POSTECH, Pohang, South Korea.
  • 2 Department of Mechanical Engineering, POSTECH, Pohang, South Korea.
  • 3 Department of Laboratory Medicine, Chonnam National University, GwangJu, South Korea.
  • 4 Department of Health Sciences and Technology, SAIHST, Sungkyunkwan University, Seoul, South Korea.
  • 5 Immunotherapy Research Center, Korea Research Institute of Bioscience and Biotechnology, Daejeon, South Korea.
  • 6 Department of Biochemistry, Microbiology and Immunology, Faculty of Medicine, University of Ottawa, Ottawa, ON, Canada.
  • 7 Laboratory Animal Science, Department of Companion, Kongju National University, Yesan, South Korea.
  • 8 Department of Materials Science and Engineering, Seoul National University, Seoul, South Korea.
  • 9 Department of Laboratory Medicine and Genetics, Samsung Medical Center, Sungkyunkwan University School of Medicine, Seoul, South Korea.
  • 10 Stem Cell and Regenerative Medicine Institute, Samsung Medical Center, Seoul, South Korea.
  • 11 Department of Health Sciences and Technology, Samsung Advanced Institute for Health Sciences and Technology, Sungkyunkwan University, Seoul, South Korea.
PMID: 31105701 DOI: 10.3389/fimmu.2019.00879
Abstract

Background: Natural Killer (NK) cell-based immunotherapy used to treat Cancer requires the adoptive transfer of a large number of activated NK cells. Here, we report a new effective method to expand human NK cells ex vivo using K562 cells genetically engineered (GE) to express OX40 Ligand (K562-OX40L) in combination with a short exposure to soluble IL-21. In addition, we describe a possible mechanism of the NK cell expansion through the OX40 receptor-OX40 ligand axis which is dependent on NK cell homotypic interaction. Methods: K562-OX40L cells were generated by lentiviral transduction and were used as feeder cells to expand and activate NK cells from PBMCs in the presence of IL-2/IL-15. Soluble IL-21 was also added in various concentrations only once at the beginning of the culture. NK cells were expanded for 4-5 weeks, and the purity, expansion rate, phenotype and function (cytotoxicity, antibody-dependent cell-mediated cytotoxicity (ADCC), cytokine production, CD107a degranulation) of these expanded NK cells were compared to those generated by using K562 feeder cells. Results: The culture of NK cells with K562-OX40L cells in combination with the transient exposure to IL-21 highly enhanced NK cell expansion to approximately 2,000-fold after 4 weeks of culture, compared to a 303-fold expansion using the conventional K562 cells. Mechanistically, the OX40-OX40L axis between the feeder cells and NK cells as well as the homotypic interaction between NK cells through the OX40-OX40L axis were both necessary for NK cell expansion. The short exposure of NK cells to IL-21 had a synergistic effect with OX40 signaling for NK cell expansion. Apart from their enhanced expansion, NK cells grown with K562-OX40L feeder cells were similar to those grown with conventional K562 cells in regard to the surface expression of various receptors, cytotoxicity, ADCC, cytokine secretion, and CD107 degranulation. Conclusion: Our data suggest that OX40 Ligand is a potent co-stimulant for the robust expansion of human NK cells and the homotypic NK cell interactions through the OX40-OX40L axis is a mechanism of NK cell expansion.

Keywords

IL-21; K562; OX40 ligand; expansion; natural killer cells.

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