Interferon production in mice by components of Salmonella minnesota R595 lipid A

The lipid A precipitate obtained by partial hydrolysis in 1% acetic acid of the glycolipid of a mutant strain of Salmonella minnesota (rough strain R595) was separated into a number of components by thin-layer chromatography. When tested as bovine serum albumin complexes, the minimal interferon-inducing dose in mice of the parent glycolipid was 0.1 mug, whereas that of lipid A was 1.0 mug. The minimal dose of the separated components ranged from 0.1 to 20 mug. The components did not differ significantly in regard to glucosamine-phosphate-fatty acid ratios. The results further emphasize that lipid A is a heterogeneous substance that contains a variety of components of differing biological activity.