MICROGLIAL CELLS INTERNALIZE AGGREGATES OF THE ALZHEIMERS-DISEASE AMYLOID BETA-PROTEIN VIA A SCAVENGER RECEPTOR

Microglia are immune system cells associated with Alzheimer's disease plaques containing beta-amyloid (A beta). Murine microglia internalize microaggregates of fluorescently labeled or radioiodinated A beta pep tide 1-42. Uptake was confirmed using aggregates of unlabeled A beta d etected by immunofluorescence. Uptake of A beta was reduced by coincub ation with excess acetyl-low density lipoprotein (Ac-LDL) or other sca venger receptor (SR) ligands, and Dil-labeled Ac-LDL uptake by microgl ia was blocked by excess A beta. CHO cells transfected with class A or B SRs showed significantly enhanced uptake of A beta. These results s how that microglia express SRs that may play a significant role in the clearance of A beta plaques. Binding to SRs could activate inflammati on responses that contribute to the pathology of Alzheimer's disease.