Detection of antinuclear antibodies in NZB and other mouse strains.

Employing formalinized chicken erythrocyte nuclei as substrate for indirect immunofluorescence assay it was possible to detect antinuclear antibodies (ANA) in the plasma of very young New Zealand Black (NZB) mice. While 7–10-day-old animals gave uniformly negative responses, weak ANA was detected in about 12 per cent of NZB mice at 14 days of age, with strong reactivity demonstrable in 90 per cent of mice by the time they were 5 weeks old. Quantification of immunofluorescence indicated that ANA reactivity of NZB plasma increased with age as measured up to 2 years.

Radiation sensitivity of New Zealand black mice and the development of autoimmune disease and neoplasia.

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.