Pyrogenic principle of the ribonucleic acid from the yeast Candida utilis.

Experiments were performed to characterize the pyrogenic principle of ribonucleic acid (RNA) from the yeast Candida utilis. It was shown that ribonuclease hydrolysis of the RNA does not lead to inactivation of the pyrogenicity. Pyrogenicity was, however, destroyed by treatment with sodium deoxycholate. On column chromatography with Biogel under sterile and pyrogen-free conditions, the pyrogenic principle of yeast RNA was eluted together with the RNA. After treatment of the RNA with ribonuclease, it was possible to separate the pyrogenic activity from the RNA (hydrolysis products) to a great extent. Column chromatography of Escherichia coli endotoxin showed that the endotoxin was eluted in the same fractions as the pyrogenic activity of yeast RNA. On the basis of the behavior of the pyrogen, it may very well be that the fever reaction is produced not by the nucleic acid but by pyrogenic contaminants of the RNA preparation.