Disease-free survival of AML and MDS patients according to specific KIR ligand absence. Kaplan-Meier estimates for the probability of disease-free survival in patients lacking the HLA-CAsn80 ligand for donor KIR2DL2/2DL3 (HLA-C group 1 absent; n = 10), patients lacking the HLA-CLys80 ligand for donor KIR2DL1 (HLA-C group 2 absent; n = 12), patients lacking the HLA-Bw4 ligand for donor KIR3DL1 (HLA-Bw4 absent; n = 6), patients lacking both an HLA-Bw4 ligand and an HLA-C ligand for donor KIR (HLA-C and HLA-Bw4 absent; n = 16), or patients with all ligands present for donor-inhibitory KIR (n = 28). Comparison of survival between patients lacking 1 KIR ligand and patients with all ligands present (P = .16), between patients lacking 2 ligands and patients lacking 1 (P = .06), and between patients lacking 2 ligands and patients with all ligands present (P = .002). Significance for heterogeneity between the study groups was tested by the log-rank statistic.