ACTIVATED MICROGLIAL CELLS ARE COLOCALIZED WITH PERIVASCULAR DEPOSITSOF AMYLOID-BETA PROTEIN IN ALZHEIMERS-DISEASE BRAIN

Background and Purpose Microglial cells are present in the center of s enile plaques (SPs) in Alzheimer's disease (AD) brain. Such a localiza tion of microglial cells suggests that they are involved in the deposi tion or the clearance of amyloid-beta protein (A beta) in the brain. W e examined their association with another type of parenchymal A beta d eposit, which is termed the perivascular deposits of A beta (PA beta). Methods Thick sections from AD brain were stained with a three-color immunofluorescence method that labeled A beta, activated microglial ce lls, and vascular endothelial cells simultaneously. Results Three-dime nsional observation under a laser scanning microscope confirmed that p erivascular aggregates of activated microglial cells were colocalized with PA beta. Conclusions Microglia occur in association with both SPs and PA beta, suggesting that they play important roles in the metabol ism of A beta in AD brain.