Lipopolysaccharide (LPS) binding in subpopulations of mouse peritoneal macrophages.

Lipopolysaccharide-binding sites of mouse peritoneal macrophages were demonstrated by means of immunogold technique. Resident peritoneal macrophages identified by peroxidatic activity in the nuclear envelope and in the rough endoplasmic reticulum show moderate and constant specific binding of bacterial lipopolysaccharide from E. coli (026:B6) to cell surface structures. Monocyte-derived macrophages with peroxidatic activity in cytoplasmic granules are characterized by a broad binding pattern. A high percentage of monocyte-derived macrophages bind large amounts of LPS-gold particles whereas some others bind only less lipopolysaccharide. This is a further hint for the existence of monocyte subpopulations. The different binding patterns of LPS after fixation and the inhibitor-ability of this binding supports the hypothesis that LPS binding is at least partly receptor-mediated.