Survival of New Zealand black × New Zealand white mice after transplantation. New Zealand black × New Zealand white mice were lethally irradiated and received either allogeneic hematopoietic stem cells, syngeneic hematopoietic stem cells, or syngeneic whole bone marrow. Mice were either 73 or 79 days of age at the time of transplantation (arrow is approximate). A subset of mice was reserved as unmanipulated age-matched controls. Survival was monitored for approximately 350 days after transplantation (420 days of age). Mice that received purified allogeneic hematopoietic stem cells (red) had significantly improved overall survival compared with the age matched control mice (gray) (P = .024) or the mice receiving syngeneic whole bone marrow (green) or hematopoietic stem cells (blue) (P ≤ .001). Radiation control mice are represented by the black dotted line. Survival curves illustrate the age of mice at death. Data were combined from 3 experiments.