In vivo antitumor responses by expanded human NK cells in the 018Z-engrafted NSG mouse model. Mice were intravenously injected with 2 × 10⁵ 018Z tumor cells and imaged by bioluminescence after 6 days to confirm tumor establishment. Then mice received either PBS (n = 11 mice) or 1 × 10⁷ human PBNK cells (n = 12 mice) at day 0 with IL-2 and IL-15 daily for the first week and IL-2 every other day for 3 more weeks. (A) Bioluminescent analyses indicate significant delay in tumor growth in mice treated with PBNK cells at days 7 and 20. (B) Kaplan-Meier survival curve of NK cell-treated and control mice. These survival data use 7 mice from the PBS-treated group and 8 mice from the PBNK cell-treated group. (C) NK-cell engraftment was evaluated by flow cytometry. Mice blood, brain, BM, spleen, lung, and liver tissues were collected from 4 mice at day 14 after PBNK treatment. NK-cell survival/engraftment was evaluated by flow cytometry for CD45⁺CD56⁺ cells in the live cell population. (D) Analysis of NK cells (CD45⁺CD56⁺ cells) in the blood and CNS at the end of the experiment when the remaining animals became moribund (n = 7 in each group). These studies demonstrate lack of penetration of NK cells into the CNS with significantly decreased NK cells in the CNS compared with peripheral blood and tissues. All statistical analyses were performed by the Mann-Whitney test in Prism 4.0.