Lipid peroxidation and storage of fluorescent products by macrophages in vitro as a model of ceroid-like pigment formation.
Storage of fluorescent products, ceroid-like pigments was observed in P388D1 cells, an established macrophage-like cell line, when the cells were cultured in the presence of rat liver phosphatidylcholine liposomes containing polyunsaturated fatty acids. Some fluorescent products accumulated in the cells were extractable in organic solvents, ethanol/ether (3:1, v/v), while others were insoluble in organic solvents, but soluble in detergent. The fluorescent products dissolved in organic solvents or in detergent had a fluorescence maximum at 430 nm when excited at 360 nm. The formation of the ceroid-like pigments was inhibited, at least in part, by antioxidants, such as alpha-tocopherol and butylated hydroxytoluene (BHT). The fluorescence intensity of the pigments was quenched in alkaline media and restored by adjustment of pH to neutrality. These findings indicate that liposome uptake by macrophages causes the formation of ceroid-like pigments, and that the fluorescent chromophores of the pigments are Schiff base structures derived from the reaction of lipid peroxides from the exogenous phospholipids and subcellular amino compounds.
Shimasaki
H
H
Department of Biochemistry, Teikyo University School of Medicine, Tokyo, Japan.
Maeba
R
R
Ueta
N
N
D000818:Animals; D000975:Antioxidants; D002460:Cell Line; D002566:Ceroid / Q000096:biosynthesis*; D004337:Drug Carriers; D015227:Lipid Peroxidation / Q000502:physiology*; D008081:Liposomes; D008264:Macrophages / Q000378:metabolism*; D008954:Models, Biological; D010713:Phosphatidylcholines / Q000378:metabolism; D013050:Spectrometry, Fluorescence
D000975:Antioxidants; D002566:Ceroid; D004337:Drug Carriers; D008081:Liposomes; D010713:Phosphatidylcholines