Therapeutic administration of regulatory T cells (Tregs) leads to engraftment of conventional
doses of allogeneic bone marrow (BM) in nonirradiated recipient mice conditioned with
costimulation blockade and mammalian target of rapamycin inhibition. The mode of action
responsible for this Treg effect is poorly understood but may encompass the control of
costimulation blockade–resistant natural killer (NK) cells. We show that transient NK cell
depletion at the time of BM transplantation led to BM engraftment and persistent chimerism …