Protein deprivation: its effects on fever and plasma iron during bacterial infection in rabbits.

1. The effects of chronic dietary protein deprivation on fever and host plasma iron reduction in bacterially infected rabbits (Oryctolagus cuniculus) were investigated. 2. Injection with Pasteurella multocida, a Gram-negative bacterium pathogenic to rabbits, led to an attenuated 24 hr fever in the protein-deprived rabbits (0.26 degrees C) compared with the 24 hr fever in the control rabbits (1.43 degrees C). 3. Plasma iron concentration remained relatively high in the protein-deprived rabbits as measured 24 hr after injection with bacteria. Total iron binding capacity did not change in the protein-deprived rabbits as measured 24 hr after injection with bacteria. 4. Inoculation of the rabbits with endogenous pyrogen from donor rabbits resulted in fever and reduction in plasma iron concentration that was of equal magnitude in the protein-deprived and control rabbits. 5. There were no differences in the concentration of total circulating leukocytes or in the differential count between the protein-deprived and control rabbits before and 24 hr after injection with bacteria. 6. These data support the hypothesis that chronic protein deprivation in rabbits results in a diminished synthesis or release, or both, of endogenous pyrogen from circulating leukocytic phagocytes, resulting in an attenuated fever and a relative hyperferremia during infection.