NKG2D is induced on CD8⁺ T cells after TCR stimulation in vitro and in vivo. (A) WT CD8⁺ T cells were activated with IL-2 alone, anti-CD3/CD28, and IL-2, or with irradiated Balb/c splenocytes for 3 days. (B) CD8⁺ T cells from P14 mice were stimulated with IL-2 alone, anti-CD3/CD28, gp33 peptide, or gp33 peptide + IL-2 for 3 days. Representative flow cytometric plots of NKG2D expression on CD8⁺ T cells are shown. (C) Irradiated Balb/c mice were transplanted with B6 TCD BM cells and B6 or NKG2D KO-derived FACS-sorted CD8⁺ T cells. On day 7, donor-derived CD8⁺ T cells were analyzed for expression of NKG2D by flow cytometry. One representative of 2 to 3 independent experiments is shown.