IVIG promotes miroglia-mediated clearance of diffuse Aβ deposits. Within the hippocampus the microglia-mediated reduction in Aβ burden was the most evident in the subiculum which displayed both dense (arrows) and diffuse (arrowheads) Aβ deposition (B). We observed primary microglia to reduce Aβ burden from the subiculum (A, n = 15, p < 0.05). IVIG further promoted the microglia-mediated clearance of Aβ (A, n = 15, p < 0.05). Diffuse Aβ deposits (arrowheads) were greatly reduced and nearly disappeared when incubated in the presence of microglia and 20 μM IVIG (B). Aβ-free cavities, present in the brain sections incubated with microglia or microglia and IVIG, are shown with asterisks (*). IVIG did not affect cell proliferation or viability as measured with cellular metabolic activity (C). Scale bar 50 μm.