Activated Microglial Cells Are Colocalized With Perivascular Deposits of Amyloid-β Protein in Alzheimer’s Disease Brain

BACKGROUND AND PURPOSE: Microglial cells are present in the center of senile plaques (SPs) in Alzheimer's disease (AD) brain. Such a localization of microglial cells suggests that they are involved in the deposition or the clearance of amyloid-beta protein (A beta) in the brain. We examined their association with another type of parenchymal A beta deposit, 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 cells, and vascular endothelial cells simultaneously. RESULTS: Three-dimensional observation under a laser scanning microscope confirmed that perivascular 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 metabolism of A beta in AD brain.