HNE-primed CTLs (donor 7) are cytotoxic to CML progenitor cells. (A) HNE-primed CTLs (CD3⁺/HNE) significantly inhibited HLA-identical CML CFU-GM colony formation. (B) Abrogation of inhibition by 10 μg antihuman mouse HLA class I antibody ^*P < .001 (t test). (C) No significant colony inhibition by untreated CD3⁺ T cells. (D) No inhibition by T cells nonspecifically expanded with IL-2 and anti-CD3 (See “CML cells express HNE and are targets for HNE-specific CTLs” for details).