Lipopolysaccharide (LPS) alters phosphatidylcholine metabolism in elicited peritoneal macrophages.

We investigated the effects of LPS on mouse peritoneal macrophage phospholipids using radiolabeled precursors. LPS (200 ng/ml) stimulated incorporation of [32P] into all classes of phospholipids within 0.5 hr, and after 2 hr the increase was 60% greater than controls. Separation of the phospholipid classes by thin-layer chromatography revealed a selective increase in incorporation of label into phosphatidylcholine (PC) (90% increase compared to approximately 50% in the other phospholipids). In macrophages labeled with [3H]-choline, LPS stimulated both the incorporation of label into PC and the release of incorporated label into the medium. The time dependencies of stimulated [3H] release and [32P] incorporation were similar. These data are consistent with the hypothesis that LPS activates macrophages via a PC-specific phospholipase-dependent mechanism.