Cumulative incidence of relapse following HCT in AML patients with inhibitory HLA-A proteins exhibiting the Bw4 epitope. Among patients without contribution of Bw4 from HLA-B alleles, the combination of patient HLA-A*24 with donor KIR3DL1 is associated with higher risk for AML relapse when compared with patients lacking HLA-A*32 and -A*24 (non-A*32/A*24), patients with HLA-A*32 and donor KIR3DL1 (A*32 + KIR3DL1^pos donor), and patients with HLA-A*24 but lacking donor KIR3DL1 (A*24 + KIR3DL1^neg donor). The KIR3DL1^pos donor group includes donors expressing either KIR3DL1^high and KIR3DL1^low or both. The KIR3DL1^neg group consist of donors expressing KIR3DL1^null/null, KIR3DL1^null/KIR3DS1, and KIR3DS1/3DS1. The indicated HR and P value reflects adjustment for year of transplant, total body irradiation, patient and donor age, conditioning regimen, T-cell depletion, graft type, disease status, cytomegalovirus, sex match, and degree of HLA match. Curve comparisons were completed using Cox proportional hazards regression analysis for the time-to-event post-HCT outcomes.