Reduction of circulating immune complexes by calorie restriction in (NZB × NZW) F₁ mice

Levels of circulating immune complexes (CIC) by the Raji cell radioimmunoassay were analyzed in sera of (NZB × NZW)F₁ ( B W) mice at four ages (3, 9, 12, and 18 months) on different levels of total food intake (Purina lab chow and two defined diets at either 20 cal/day or 10 cal/day). In all three groups of animals the CIC levels at 3 months of age were essentially normal irrespective of dietary intake and increased dramatically in sera of mice of both sexes at 6 and 9 months. The highest CIC values were recorded just prior to death at 12 months of age in sera of mice fed Purina lab chow. In contrast, significantly lower CIC values were observed at 12 months of age on the 10-cal intake (P < 0.001). C3 and Ig deposits in the kidney lesions of the mice were strikingly less in those mice fed the 10-cal diet than those fed either of the other two diets. This value was also significantly lower than that of the animals fed 20 cal per day of a defined diet. These findings suggest that diet may influence lifespan of the shortlived autoimmune-prone B W mice by inhibiting the formation and deposition of immune complexes in vital organs.