IL15 and graft versus host disease: We therefore set out to address the effect of IL‐12/15/18‐preactivated NK cells from B6 mice on acute GvHD in comparison with both IL‐15‐preactivated NK cells and NK cells activated with IL‐2, using a mouse model of fully mismatched transplantation in which donor allogeneic T cells from the spleens of B6 mice (H‐2b) are adoptively transferred to BALB/c mice (H‐2d).