Vitamin A induced nonspecific resistance to infection

The effect of vitamin A on resistance to infection was evaluated. Mice treated with four consecutive daily injections of 3,000 international units of vitamin A palmitate and then challenged with either a gram negative bacterium (Pseudomonas aeruginosa), a gram positive bacterium (Listeria monocytogenes), or a fungus (Candida albicans), showed a significant decrease in total mortality or mortality rate compared with control animals. Five hours after challenge with P. aeruginosa, the mice treated with vitamin A had sterile blood, whereas the control animals showed persistent bacteremia until death. However, the clearance of colloidal carbon or aggregated human serum albumin by the reticuloendothelial system was unaltered by treatment with vitamin A. In addition, vitamin A did not affect in vitro growth of the three challenge organisms. These studies demonstrate that vitamin A induces nonspecific resistance to infection in mice.