KLRK1 and paroxysmal nocturnal hemoglobinuria: Cell killing assays using autologous NK cells and NKG2D-expressing T cells demonstrated killing of granulocytes from PNH patients expressing NKG2D ligands (83), and blocking NKG2D by antibodies improved hematopoietic progenitor colony formation by bone marrow mononuclear cells from AA and PNH patients (82).