Pl. Dipatre et Bb. Gelman, MICROGLIAL CELL ACTIVATION IN AGING AND ALZHEIMER-DISEASE - PARTIAL LINKAGE WITH NEUROFIBRILLARY TANGLE BURDEN IN THE HIPPOCAMPUS, Journal of neuropathology and experimental neurology, 56(2), 1997, pp. 143-149
Microglial cells are the main component of the brain's resident immune
system and are activated in Alzheimer disease (AD). We quantified the
density of activated microglial cells (AMG) in 8 sectors of human hip
pocampus to determine if their density is correlated with senile plaqu
e (SP) and neurofibrillary tangle (NFT) formation. Ferritin-stained mi
croglia, Bielschowsky-stained neuritic plaques, and perikarya containi
ng NFTs were counted in 8 young adults, 9 nondemented elderly adults,
and 9 demented patients with AD. Microglial cell activation was modera
tely higher in elderly nondemented subjects. In AD there was a more st
riking activation in all sectors of the hippocampus. Most AMGs were di
stributed diffusely in neuropil and were not delimited to SPs or NFTs.
Senile plaque counts were not linked with AMG counts within any secto
r. Neurofibrillary tangle counts were correlated significantly with AM
G counts within one sector, the subiculum. When variations within and
between sectors were factored out statistically, the burden of AMGs wa
s correlated significantly with the burden of NFTs (r = 0.34; p < 0.00
5), but not SPs. Neuropathologic changes at the origin of the perforan
t pathway were correlated significantly with orthograde microglial cel
l activation in the termination field. These observations show that co
rrelations between microglial cell activation and pathologic features
of AD are only rarely significant. When significant linkage was presen
t, it involved NFTs and not SPs, and depended on which sector of hippo
campus was examined.