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pubmed:abstractText |
Young New Zealand Black (NZB) mice manifested extremely high resistance to the lethal effects of acute exposures to ionizing radiation, with a dose necessary to kill 50% of the animals within 30 days, LD(50(30)), of 964 roentgens (R) at 30 days of age and of 856 R for 90-day-old mice. In contrast, Coombs' positive 9-month-old NZB mice (with low primary immune response) were highly susceptible (LD(50(30)) = 543 R), possibly because of anemia-stimulated erythropoiesis leading to a depletion of stem cells. The radiation resistance of young NZB mice, combined with previous observations of their immunologic hyper-responsiveness, support the concept that NZB mice possess an unusually large pool of hematopoietic stem cells, an abnormality which may predispose them to the development of autoimmune disease and neoplasia.
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