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. During the first year of life, mice of C57B1, CBA, C3H, BALB/c, AKR, A, SJL and 129/J strains manifested largely negative and weak reactions. However, by 1–2 years of age these animals showed marked increases in incidence of strongly reactive ANA.