IL-15-dependent engraftment of CMV-specific T_CM/E cells in NOG mice is greater than that of T_EM/E. (A) Schematic of the experiment. (B) Mean percentage (± SE) of human T cells (CD45⁺ CD8⁺) in peripheral blood lymphocytes (PBLs) of mice engrafted with T_CM/E (squares) or T_EM/E (circles) was determined by flow cytometry (n = 5). *P < .05, T_CM/E versus T_EM/E cell engraftment in the presence of NS0-IL-15 cells (unpaired Student t test). (Inset) Mean levels of human IL-15 (± SE) in day 7 serum of NOG mice that had received 3 intraperitoneal injections of 1.5 × 10⁷ irradiated NS0-IL-15 cells (n = 6) or in control mice (n = 10). (C) Mean percentage of human T cells (CD45⁺ CD8⁺) plus or minus SE in mouse PBL, bone marrow, and spleen at day 21. *P < .05, T_CM/E cell engraftment in each organ versus that of T_EM/E in the presence of NS0-IL-15 cells. (D) TCR Vβ repertoire of the CMV-specific T_CM/E and T_EM/E before (Input) and after (d21) engraftment. Percentage of CD3⁺ cells (Input) or CD45⁺ CD3⁺ cells (d21) that were positive for the indicated TCR Vβ genes was determined by flow cytometry.