Induction of Resistance to Bacterial Infections of Mice with Poly I·poly C

RECENT reports describe the protective action of poly-inosinic–polycytidylic acid (poly I·poly C), an inducer of interferon, on non-viral diseases (refs. 1 and 2 and personal communication of P. Actor, D. Kunkel, M. Goore, S. Garg and J. Pagano). Poly I·poly C also accelerates homograft rejection 3 and enhances the immunological response of animals to injection with influenza vaccine 4 . Such activities are reminiscent of those of classical endotoxin. Treatment of mice with either substance is capable of inducing tolerance to subsequent challenge with lethal doses of endotoxin or poly I·poly C 5 . Both substances have also been shown pyrogenic for the rabbit 6 and both are abortifacient 7,8 .