Hematopoietic stem cell transplantation: killer immunoglobulin-like receptor component

Area of Science:

• Immunogenetics
• Transplantation immunology
• Hematologic oncology

Background:

• Donor natural killer (NK) cell killer immunoglobulin-like receptors (KIR) interact with recipient human leukocyte antigen (HLA) class I ligands.
• This interaction is hypothesized to mediate anti-leukemia allograft reactivity, potentially improving outcomes in acute myelogenous leukemia (AML) patients post-hematopoietic cell transplantation (HCT).

Purpose of the Study:

• To investigate the association between KIR-ligand mismatches and relapse risk in patients undergoing myeloablative, T-replete HCT from unrelated donors.
• To identify predictive factors for leukemia relapse based on KIR-ligand interactions.

Main Methods:

• Analysis of 1770 patients undergoing myeloablative T-replete HCT from HLA-matched or mismatched unrelated donors.
• Evaluation of the impact of recipient KIR ligand status on relapse hazards.
• Statistical analysis including hazard ratios (HR) and confidence intervals (CI).

Main Results:

• Lack of inhibitory KIR ligands in patients was associated with significantly lower relapse hazards in HLA-mismatched transplants (HR: 0.061; P=0.004).
• Absence of specific KIR ligands, HLA-C group 2 or HLA-Bw4, independently correlated with reduced relapse hazards (HR: 0.47, P=0.004 and HR: 0.56, P=0.04, respectively).

Conclusions:

• Recipient homozygosity for HLA-B or -C epitopes defining KIR ligands may predict leukemia relapse risk after myeloablative HCT from unrelated donors.
• KIR genotyping of unrelated donors and recipients is crucial for understanding the role of these receptors in HCT outcomes and optimizing transplant strategies.