Natural killer (NK) cells were first identified and named for their “natural” cytotoxicity to reject bone-marrow allografts in lethally irradiated mice. Different from T cells, NK cells require no prior sensitization or immunization to lyse transformed or virally infected target cells and are non-major histocompatibility complex (MHC)–restricted. However, recent progress in understanding of NK cells biology has proved that NK cells share some similar characteristics with T cells. During development, NK cells also undergo “education” according to “missing self” principle, thereby become mature and acquire effector function. The discovery that NK cells are able to “remember” prior certain stimulations indicates they may also contribute to adaptive immunity. After hematopoietic stem cell transplantation (HSCT), NK cells are the first donor-derived lymphogenous cells to reconstitute and alloreactivitiy of donor-derived NK cells have been shown to mediate graft-versus-leukemia (GvL) effect rather than to induce graft-versus-host disease (GvHD). These properties make donor-derived NK cells appealing for applications to benefit the outcome of HSCT. Here, we will review the improved understanding of NK cell biology, discuss characteristics of donor-derived NK cells which are associated with beneficial outcome of HSCT and explore novel methodologies that enhance the therapeutic effect of donor NK cells.
Part of the book: Natural Killer Cells