LIPID OXIDATION, LIPOPROTEIN CELL-ASSOCIATION AND CEROID ACCUMULATIONIN P388D1 MACROPHAGE-LIKE CELLS

Flow cytometry can be used to quantify the accumulation of ceroid in m acrophages, the result of cellular handling of certain lipoproteins. U sing P388D1 cells, a murine-derived macrophage-like cell line, the eff ect of the lipophilic antioxidant, DL-alpha-tocopherol, upon the uptak e and accumulation of ceroid by the cells was monitored on culture wit h artificial lipoproteins containing a single lipid species. Ceroid ac cumulation was greater for artificial lipoprotein composed of BSA comp lexed with cholesteryl arachidonate, than with cholesteryl linoleate. alpha-Tocopherol inhibited the ceroid accumulation, which was also dep endent upon cell density. Thus, since these findings are similar to re cent observations in primary cultures of murine peritoneal macrophages , it would appear that macrophage-like cell lines such as P388D1 cells are appropriate for the study of potential agonists and antagonists o f lipid oxidation. Culture of P388D1 cells with oxidised human low-den sity lipoprotein (LDL) also resulted in ceroid formation, shown to be dependent upon the level of LDL oxidation as assessed by thiobarbituri c acid-reactivity, the xylenol orange assay of peroxides and gas chrom atographic analysis of cholesterol and fatty acid content. Ceroid accu mulation reflected changes in the level of LDL oxidation better than d id the cell association of oxidised radiolabelled LDL, monitored as th at bound and retained by the cell.