Function of NKG2D in natural killer cell-mediated rejection of mouse bone marrow grafts

Irradiation- resistant natural killer ( NK) cells in an F-1 recipient can reject parental bone marrow, and host NK cells can also prevent engraftment of allogeneic bone marrow. We show here that repopulating bone marrow cells in certain mouse strains expressed retinoic acid early inducible 1 proteins, which are ligands for the activating NKG2D NK cell receptor. Treatment with a neutralizing antibody to NKG2D prevented rejection of parental BALB/ c bone marrow in ( C57BL/ 6 x BALB/ c) F1 recipients and allowed engraftment of allogeneic BALB. B bone marrow in C57BL/ 6 recipients. Additionally, bone marrow from C57BL/ 6 mice transgenic for retinoic acid early inducible 1 epsilon was rejected by syngeneic mice but was accepted after treatment with antibody to NKG2D. If other stem cells or tissues upregulate expression of NKG2D ligands after transplantation, NKG2D may contribute to graft rejection in immunocompetent hosts.