Effect of detoxification processes on the interferon-inducing activity of bacterial endotoxins

The interferon (IFN)-inducing activity of detoxified lipopolysaccharide (LPS) was tested in rabbits treated with LPS preparation derived from Escherichia coli, Salmonella typhi, Salmonella enteritidis and Shigella dysenteriae serovar 1. Of the detoxification procedures used, alkaline hydrolysis, hydroxylaminolysis, formalization, treatment with sodium deoxycholate and the radiodetoxification (fast or slow) methods had no appreciable effects on the IFN-inducing potential of LPS. In contrast, acetylation or prolonged alkaline hydrolysis of LPS resulted in up to a 9-fold reduction of IFN-induction capacity and effects of Cu++ or Fe++ cations bound to LPS were clearly inhibitory (Fe more than Cu).