In vivo targeting of CD8⁺ cells. (A) Outline of the experimental setup. Human PBMCs were activated for 3 days after isolation, and 1 × 10⁷ cells were intraperitoneally injected into NOD-scid-IL2rγ^null mice. One week later, CD8-LV particles (8 × 10⁵ transduction units per mouse), or PBS as a control, were intraperitoneally injected. Peritoneal cells were collected 1 week after vector injection and analyzed by flow cytometry. (B) Representative FACS data demonstrating specific transduction of human CD8⁺ T cells in the peritoneal cavity. Isolated peritoneal cells from PBS or CD8-LV–injected mice were stained with anti–human CD8 mAb, and the percentage of human CD8⁺/GFP⁺ cells was analyzed. (C) Percentages of GFP⁺ cells in hCD8⁺ T cells (gray bars) and hCD8⁻ T cells (white bars) were calculated according to panel B. Results are expressed as mean ± SEM (n = 4; *P < .05; nd indicates not detectable).