Macrophage activation in response to S-form lipopolysaccharides (LPS) separated by centrifugal partition chromatography from wild-type LPS: effects of the O-polysaccharide portion of LPS.

The S-form lipopolysaccharide (LPS) was effectively separated from a native preparation of smooth-type Salmonella abortus equi LPS by means of the centrifugal partition chromatography (CPC). To clarify the mechanisms by which LPS activates macrophages, CPC-separated S-form LPS was assessed for its ability to induce the secretion of tumor necrosis factor-alpha (TNF-alpha) by murine macrophage-like J774.1 cells in comparison with other fractions of LPS which lacks most of O-polysaccharides. LPS dose-response and time-kinetics studies showed that serum factor(s) regulated especially the onset of TNF-alpha secretion in stimulation with S-form LPS. These results strongly suggest that the native (unfractionated) LPS activates macrophages in both O-polysaccharide/serum-dependent and -independent pathways.