CORPORA-AMYLACEA COULD BE AN INDICATOR OF NEURODEGENERATION

We describe an investigation of corpora amylacea (CA) in the brain tis sue of Alzheimer's disease (AD) cases and normal ageing controls, usin g both light (LM) and electron (EM) microscopic techniques. CA populat ions were shown by routine histological staining of LR White resin sec tions with methenamine silver and PAS, and were compared with those sh own by immunocytochemistry using antibodies to tau, GFAP, tubulin, ubi quitin, beta-amyloid and serum amyloid P component in serial sections. All CA were immunoreactive with anti-tau and all were unreactive with anti-beta-amyloid. Most were immunoreactive with anti-serum amyloid P component, although this was often weak in AD. CA from normal ageing brain were immunoreactive for proteins that are associated with the ne uronal cytoskeleton and cell injury. CA from AD brain shared some of t hese but differed from those in normal ageing brain by being in much l arger number and more variable in their immunoreactivity. In all CA, X -ray microanalysis illustrated the presence of the metallic elements C a, Fe and Cu. Aluminium, often associated with AD, was not present, ev en in CA from AD brain. Phosphorus and sulphur, probably from phosphor ylated proteins associated with degenerating cytoskeleton elements, we re usually detected. In AD brain, the greater numbers of CA and their variable biochemical and elemental composition, when compared with CA in the normal ageing brain, suggests that they may derive from a numbe r of sources both neuronal and glial as a result of the neurodegenerat ive disease.