Dietary Influence on Breeding Behavior, Hemolytic Anemia, and Longevity in NZB Mice

NZB mice are extensively used throughout the world as a model system for studying autoimmune disease. Apparently associated with a propensity to early development of autoimmune hemolytic anemia, the breeding capacity of NZB mice is defective; and the life span of these animals is short. As part of a general effort to improve breeding in our colonies, comparison of the influence of two commercial diets on NZB mice was made. One diet provided low protein and relatively high fat; the other, somewhat higher protein and lower fat content. Improved breeding performance was observed in the animals fed higher fat, lower protein intake. But, this diet influenced the animals adversely by fostering development of hemolytic anemia and shortening the life span both in males and females; whereas higher protein and lower fat extended particularly the longevity of male mice. These observations are taken as preliminary evidence that dietary intake can profoundly influence the development of autoimmune disease and to suggest that further systematic studies must be carried out to dissect more specifically the nature of these dietary influences. High titers of transplantation antibodies, as measured by a hemagglutination test, were induced in Buffalo strain rats by repeated inoculations of a carcinogen-induced tumor maintained in Fischer-344 rats. This tumor grew in Buffalo rats immu-nosuppressed by X-irradiation and cortisone. When a gamma globulin fraction from pooled immune serum was injected intravenously into such tumor-bearing rats the antibody titer in blood declined more rapidly than in similar immunosuppressed rats without tumor transplants.