Association between pre-transplant natural kill and graft-versus-host disease after stem-cell transplantation.

Natural killer activity against herpes simplex virus type 1 infected fibroblasts NK(HSV-1) was studied prospectively in patients undergoing allogenic bone-marrow or fetal-tissue stem-cell transplantation. Thirteen patients showed evidence of engraftment and survived long enough to develop graft-versus-host disease (GvHD). Of this group, all of the seven having normal NK(HSV-1) activity before transplantation acquired GvHD and the six having low NK(HSV-1) had no evidence of GvHD. These results were independent of mode of preparation of patients for transplantation, source of stem cells used, or cytomegalovirus infections, and they suggest that this assay reflects a host-determined function capable of stimulating GvHD.