Use of NK cell activity in cure by transplant.

Analogous to T cells, Natural Killer (NK) cells may facilitate engraftment, combat infection, and control cancer in bone marrow or haematopoietic stem cell transplantation (HSCT); however, NK cells do not cause graft-versus-host disease. Killer immunoglobulin-like receptors (KIRs) regulate NK cell function, and recent data suggest that KIR is as important as its ligand (human leucocyte antigen; HLA) in HSCT for both malignant and non-malignant conditions. Because there is substantial variability in KIR gene content, allelic polymorphism, and cell-surface expression among people, careful selection of donors based on HLA and KIR is essential to optimize HSCT outcomes. Furthermore, NK cells may be used for adoptive immunotherapy after HSCT in place of conventional donor lymphocyte infusion, as part of pre-transplant cytoreductive therapy, or as an independent therapeutic agent in high-risk leukaemia in place of sibling donor HSCT.