IL2 and graft versus host disease: The mechanisms by which this inhibition occurred may well contribute to suppressing GvHD, but remains to be defined, although it is likely that upregulation of the high‐affinity receptor for IL‐2 (CD25) on IL‐12/15/18‐preactivated NK cells makes them sequester IL‐2 by which they may outcompete donor T cells 20.