Natural Killer (NK) Cell Alloreactivities against Leukemic Cells: Functions beyond Defense

Immunotherapy using adoptive transfer of natural killer (NK) cells has progressively been utilized in hematologic malignancies over the past decade. Presently, NK cell immunotherapy has been promising and feasible in acute leukemia, particularly in acute myeloblastic leukemia (AML). Alloreactive NK cells have been exploited under the killer immunoglobulin-like receptor (KIR)-ligand mismatches between donors and recipients in haploidentical hematopoietic stem cell transplantation (haplo-HSCT) after immunosuppressive chemotherapy. Of interest, alloreactive NK cells killed residual leukemic cells, dendritic cells (DCs) and T cells in acute leukemia patients and led to significantly improved clinical outcomes. Consequently, this chapter provides the KIR genetics and the mechanisms of alloreactive NK cells that are shown to be crucial in the successful therapy of acute leukemia (myeloid and lymphoid). Altogether, the donor selection algorithm of haplo-HSCT is discussed to emphasize the importance and give priority to increase the chances of therapy success. These will be useful for students and researchers who work in immunogenetics. Furthermore, the knowledge would be applicable to clinical research and medical sciences