Aβ inhibits lysosomal degradation of oxidized LDL and cholesterol ester accumulation in macrophages. A. Fibrillar Aβ, but not revAβ, dose-dependently inhibits lysosomal degradation of 125I-oxLDL by macrophages, similar to unlabeled oxLDL competitor (B). C. Intracellular accumulation of Aβ does not block lysosomal degradation of 125I-oxLDL. Macrophages were pretreated with 20 μM Aβ or revAβ for 3 hours to allow intracellular accumulation, washed extensively to remove extracellular peptide and degradation of 125I-oxLDL over 5 h was measured in the absence (PT) or presence of additional peptide. D. Aβ blocks cholesterol ester accumulation in oxLDL treated macrophages. Cellular lipids were extracted from macrophages treated with oxLDL (40 μg/ml) for 48 h in the presence or absence of 20 μM Aβ and analyzed by gas-chromatography mass-spectrometry. Cholesterol ester content was normalized to cellular protein. (A-D) Data are the mean of triplicate samples ± standard deviation, *p ≤ 0.005.