Natural Killer Cells and Allogeneic Hematopoietic Cell Transplantation

Natural killer (NK) cells are part of the innate immune system. These cells recover quickly after blood and marrow transplantation and have been implicated in graft-versus-leukemia reactions, engraftment, rejection and infection protection. NK-cell activation is controlled by a complex series of receptors that recognize MHC or MHC-like molecules that are present on the surface of potential target cells. NK effector function includes direct cytotoxicity and cytokine production. NK cells interact with a variety of components of the immune system, including dendritic cells. Recent studies suggest that it may be possible to choose related or unrelated donors based on the presence or absence of certain NK-cell genes (i.e., killer-cell immunoglobulin-like receptor) and that this might influence the risk of relapse. Lastly, adoptive cellular therapy studies with purified and cultured NK cells are ongoing and hold promise as a non-toxic, effective anticancer therapy.