title: Expansion of highly cytotoxic human natural killer cells for cancer cell therapy.
abstract: Infusions of natural killer (NK) cells are an emerging tool for cancer immunotherapy. The development of clinically applicable methods to produce large numbers of fully functional NK cells is a critical step to maximize the potential of this approach. We determined the capacity of the leukemia cell line K562 modified to express a membrane-bound form of interleukin (IL)-15 and 41BB ligand (K562-mb15-41BBL) to generate human NK cells with enhanced cytotoxicity. Seven-day coculture with irradiated K562-mb15-41BBL induced a median 21.6-fold expansion of CD56(+)CD3(-) NK cells from peripheral blood (range, 5.1- to 86.6-fold; n = 50), which was considerably superior to that produced by stimulation with IL-2, IL-12, IL-15, and/or IL-21 and caused no proliferation of CD3(+) lymphocytes. Similar expansions could also be obtained from the peripheral blood of patients with acute leukemia undergoing therapy (n = 11). Comparisons of the gene expression profiles of the expanded NK cells and their unstimulated or IL-2-stimulated counterparts showed marked differences. The expanded NK cells were significantly more potent than unstimulated or IL-2-stimulated NK cells against acute myeloid leukemia cells in vitro. They could be detected for >1 month when injected into immunodeficient mice and could eradicate leukemia in murine models of acute myeloid leukemia. We therefore adapted the K562-mb15-41BBL stimulation method to large-scale clinical-grade conditions, generating large numbers of highly cytotoxic NK cells. The results that we report here provide rationale and practical platform for clinical testing of expanded and activated NK cells for cell therapy of cancer.
authors.affiliation: Department of Oncology, Hartwell Center for Bioinformatics and Biotechnology, St Jude Children's Research Hospital, Memphis, Tennessee 38105, USA.
authors.forename: Hiroyuki
authors.initials: H
authors.lastname: Fujisaki
authors.forename: Harumi
authors.initials: H
authors.lastname: Kakuda
authors.forename: Noriko
authors.initials: N
authors.lastname: Shimasaki
authors.forename: Chihaya
authors.initials: C
authors.lastname: Imai
authors.forename: Jing
authors.initials: J
authors.lastname: Ma
authors.forename: Timothy
authors.initials: T
authors.lastname: Lockey
authors.forename: Paul
authors.initials: P
authors.lastname: Eldridge
authors.forename: Wing H
authors.initials: WH
authors.lastname: Leung
authors.forename: Dario
authors.initials: D
authors.lastname: Campana
mesh_terms: D000328:Adult; D000818:Animals; D018922:HL-60 Cells; D006801:Humans; D016219:Immunotherapy, Adoptive / Q000379:methods*; D007376:Interleukin-2 / Q000494:pharmacology; D020014:K562 Cells; D007694:Killer Cells, Natural / Q000187:drug effects / Q000276:immunology*; D015470:Leukemia, Myeloid, Acute / Q000097:blood / Q000276:immunology / Q000628:therapy*; D051379:Mice; D016688:Mice, Inbred NOD; D016513:Mice, SCID; D054198:Precursor Cell Lymphoblastic Leukemia-Lymphoma / Q000097:blood / Q000276:immunology / Q000628:therapy*; D020298:U937 Cells
chemical_list: D007376:Interleukin-2