ApoE-derived peptides significantly decrease Aβ1-40 levels in PS70 cells. PS70 cells were treated with the apoE monomer (n = 6, A), dimer (n = 6, B), or trimer (n = 6, C) for 24 h at various concentrations. Aβ1-40 levels in the conditioned media were determined by ELISA (n = 6). The apoE monomer decreased Aβ1-40 by 20% at 30 nM and 100 nM (p < 0.05) and by 30% at 300 nM, 1 μM, and 3 μM (p < 0.01). The apoE dimer decreased Aβ1-40 by 35% at 30 nM (p < 0.01), 51% at 100 nM, 64% at 300 nM, 77% at 1 μM, and 90% at 3 μM (p < 0.001 for all). The apoE trimer decreased Aβ1-40 by 68% at 100 nM, 72% at 500 nM, and 85% at 1 μM (p < 0.001 for all). D. Human Aβ1-40 was measured from samples containing the apoE dimer peptide alone, synthetic human Aβ40 alone, synthetic human Aβ40 with PBS, or synthetic human Aβ40 with apoE dimer peptide. Aβ1-40 values were normalized to background with apoE dimer peptide alone, and were not found to be significantly different in the presence of PBS or apoE dimer peptide.