Purified CD8+ T cells were cultured on plate-bound anti-NKG2D (1 μg/ml) or isotype control (mIgG1) for 24 h before the NKG2D expression was measured by flow cytometry. Means and SD of MFI (upper panel) and percentage of NKG2D+ cells (lower panel) are shown (n = 6). Differences between the groups were analyzed by t-tests, and the P-values are indicated. 