KIR3DL1 and acute myeloid leukemia: The first evidence for the therapeutic effectiveness of natural killer (NK) cells in AML was established in a study of 57 adult patients, in which none of the 20 individuals who received haploidentical cell transplantation from a killer immunoglobulin–like receptor (KIR)–human leukocyte antigen (HLA)-mismatched donor experienced disease relapse [2].