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Updated: May 18, 2026
Expansion, Purification, and Functional Assessment of Human Peripheral Blood NK Cells
Published on: February 2, 2011
Improved expansion of peripheral blood and iPSC-derived natural killer cells for clinical applications
Jaya Lakshmi Thangaraj1, Edith Lopez1, Dan S Kaufman1
1Department of Medicine, Division of Regenerative Medicine, University of California, San Diego, La Jolla, CA, USA; UCSD Sanford Stem Cell Institute, La Jolla, CA, USA.
The large-scale expansion of natural killer (NK) cells commonly relies on artificial antigen-presenting cells (aAPCs). Currently, K562 cells expressing 41BBL and membrane-bound IL-21 (mbIL-21) are widely used to expand NK cells for clinical use. Here, we explored whether alternative aAPCs could improve NK cell expansion and better support clinical translation. We developed and tested four genetically modified feeder cell lines as alternative aAPC sources. K562 and 721.221 cells were engineered to express either OX40L or 41BBL, along with mbIL-18/21 and B7H6. We evaluated the expansion of NK cells derived from 3 different sources: unfractionated peripheral blood mononuclear cells (PBMCs), peripheral blood (PB), and induced pluripotent stem cells (iPSCs). Our results showed that 721.221 feeder cells expressing 41BBL-B7H6 or OX40L with mbIL-18/21 significantly enhanced NK cell expansion compared with K562 cell-based aAPCs. All modified aAPCs induced strong NK cell activation and tumor-killing activity. These findings identify 721.221 cell-derived 41BBL-B7H6-mbIL-18/21 cells as promising aAPCs for large-scale NK cell production in clinical settings.
The large-scale expansion of natural killer (NK) cells commonly relies on artificial antigen-presenting cells (aAPCs). Currently, K562 cells expressing 41BBL and membrane-bound IL-21 (mbIL-21) are widely used to expand NK cells for clinical use. Here, we explored whether alternative aAPCs could improve NK cell expansion and better support clinical translation. We developed and tested four genetically modified feeder cell lines as alternative aAPC sources. K562 and 721.221 cells were engineered to express either OX40L or 41BBL, along with mbIL-18/21 and B7H6. We evaluated the expansion of NK cells derived from 3 different sources: unfractionated peripheral blood mononuclear cells (PBMCs), peripheral blood (PB), and induced pluripotent stem cells (iPSCs). Our results showed that 721.221 feeder cells expressing 41BBL-B7H6 or OX40L with mbIL-18/21 significantly enhanced NK cell expansion compared with K562 cell-based aAPCs. All modified aAPCs induced strong NK cell activation and tumor-killing activity. These findings identify 721.221 cell-derived 41BBL-B7H6-mbIL-18/21 cells as promising aAPCs for large-scale NK cell production in clinical settings.
