Comparative study of NZB mice under germfree and conventional conditions.

Groups of New Zealand Black (NZB) mice born and reared in germfree conditions were studied at three, six, nine, and 12 months of age. Compared with NZB mice of the same ages raised under conventional conditions, the germfree mice showed: (1) significantly lower gamma-globulin levels, (2) significantly higher frequency of serum antinuclear factor (ANF), and (3) significant decreases in the incidence and severity of renal disease. The lower gamma-globulin levels probably reflect lack of antigenic stimulation by common bacteria. The higher frequency of ANF may be a chance finding or may reflect lack of deposition of complexes in the kidneys. The latter also may explain the decreased severity of renal disease. It is possible that complexes of antibody with common antigens (such as bacteria) may deposit in diseased kidneys and aggravate the condition.