IMPACT OF MONOCYTE COLONY-STIMULATING FACTOR UPON BETA-VERY LOW-DENSITY-LIPOPROTEIN (BETA-VLDL) CHOLESTEROL-METABOLISM IN TETRADECANOYL PHORBOL ACETATE-DERIVED THP-1 CELLS

The effect of monocyte colony stimulating factor (M-CSF) on the beta-v ery low density lipoprotein (beta-VLDL) metabolism in THP-1 cells (hum an leukemia cell line) was studied. THP-1 cells treated with M-CSF dec reased Latex Bead phagocytosis, but the cells incubated with 12-tetrad ecanoyl-phorbol-13-acetate (TPA) enhanced phagocytosis 2.5-fold. Bindi ng activity of I-125-M-CSF to THP-1 cells was higher than that in THP- 1 cells elicited with TPA. THP-1 cells incubated with M-CSF before TPA treatment were designated MT macrophages, and these incubated with M- CSF after TPA treatment were called TM macrophages. When these cells w ere incubated with beta-VLDL, the cholesterol ester content in MT macr ophages was less than in TM macrophages. The uptake of [H-3]cholestero l oleate-beta-VLDL in MT macrophages was the same as in TM macrophages . The released radioactivity from [H-3]cholesterol oleate-beta-VLDL lo aded MT macrophages was higher than that from TM macrophages. Acid cho lesterol esterase activity and ACAT activity were the same in both typ es of macrophages. Neutral cholesterol esterase activity was higher in MT than in TM macrophages. These results suggested that beta-VLDL-ind uced cholesterol ester deposition in THP-1 cells-derived macrophages w as suppressed by M-CSF, when M-CSF acted at the stage of monocytes (TH P-1 cells), and that the reduction of cholesterol ester might be due t o enhanced release of cholesterol from the cells with high neutral cho lesterol esterase activity.