Fractionation of immune RNA isolated from the spleens of mice infected with Trypanosoma cruzi.

Immune RNA was extracted from the spleens of mice infected with Trypanosoma cruzi. The immunologic activity of crude immune RNA and the fractions that were obtained by sucrose density gradient centrifugation was assessed by the in vitro macrophage migration-inhibition assay. Crude immune RNA can convert nonsensitized mouse peritoneal cells to a state of specific immunologic reactivity to T. cruzi antigens. The transfer activity of crude immune RNA was abolished by treatment with pancreatic ribonuclease. The 4S-5S RNA was the only fraction active in transferring delayed hypersensitivity in experimental Chagas' disease; however, the 4S transfer RNA also isolated from the spleens of mice with Chagas' disease has no immunologic activity. Immune RNA in experimental Chagas' disease may be an informational RNA.