The induction of delayed hypersensitivity in guinea pigs to poly U and poly A:U.

Guinea pigs were sensitized to poly U and poly A:U so that subsequent stimulation of spleen cells from these immunized animals with poly U and poly A:U resulted in the production of migration inhibitory factor (MIF). MIF was also produced when spleen cells from animals immunized with poly A:U were cultured in the presence of mycobacterial RNA or whole viable H37 Ra cells. Negative dermal reactions were observed when guinea pigs immunized with poly A, poly A:U were skin tested wtih these same synthetic nucleotides.