NK cells directly lyse activated, donor Tcons in an NKG2D-dependent manner. (A) Activated NK cells alone (solid line) or incubated with isotype control antibody (dashed line) lysed donor Tcon reisolated from spleen and lymph node of transplant recipients. Lysis was significantly reduced with NKG2D-blocking antibody at a 20:1 effector to target ratio and for LN at a 5:1 E/T ratio (*P < .01, **P < .001, 5:1 spleen was NS). Data are an average of triplicates. (B) Expression of the NKG2D ligand Rae1γ was higher on donor CD4⁺ and CD8⁺ cells reisolated from lymph node and spleen on day 5 than naive, freshly isolated T cells as detected by FACS analysis. Data are representative of 3 experiments. (C) The MFI of Rae1γ NKG2D ligand expression was significantly higher on activated CD69⁺ than CD69⁻ CD4⁺ and CD8⁺ cells from spleen and lymph node (***P < .001). Data are pooled from 3 mice per group and are representative of 2 experiments.