Neuropathological diagnosis of Alzheimer's disease: a comparison between
that using CERAD's staining techniques to that using KM+ lectin.
Oliveira1,2, A.O.; Neder3, L.; Rosemberg4, S.; Chimelli5, L.; Anselmi2,3, A.M.; Corrêa6, V.M.A., Jacob4 Filho, W., Grinberg4, L. and Martins2, A.R.
Dept of Psycobiology1, FFCLRPUSP; Depts of Pharmacology2 and Morphology FMRP-USP; Depts of Pathology FMRPUSP3, FMUSP4 , UFRJ5.
KM+ is a D(+) mannose-binding lectin from Artocarpus integrifolia that binds to several brain glicoconjugates. Alzheimer's disease (AD) is a progressive dementia, characterized by a specific pattern of brain pathological changes. We show a comparison of detection of senile plaques in AD brains using the Bielschowsky staining versus lectin KM+.
Brains obtained at autopsy from patients with clinically diagnosed AD were formalin-fixed, and paraffin-embedded. AD diagnosis was done according to CERAD¢s criteria. Sections of hippocampus and temporal cortex were stained with hematoxylin-eosin, Congo red, and silver by a Bielschowsky method. Brain sections were stained for KM+ binding sites (BS) after antigen retrieval, using biotynil- KM+ (0.18mg/ml), and the ABC method with DAB as chromagen. Semiquantitative assessment of AD was based on the number of neocortical senile plaques per 100x microscopic field, estimated using Bielschowsky and KM+ BS. Brain tissues obtained at autopsy without evidence of neuropathological alterations and without clinical history of neurological disease were used as controls (29 cases), and were matched for age and sex with AD tissues. Correlation between these diagnostic methods was tested using the Spearman method.
KM+ BS were strongly labeled in neuritic and amorphous types of senile plaques, dystrophic neurites and neurofibrillary tangles in nine brains of AD, two cases Down's syndrome, and cortex of nine patients obtained at autopsy lacking clinical diagnosis of dementia. Control nerve cells were also stained. There was a correlation (-0.783) between both diagnostic procedures in the hippocampus, but not in the temporal cortex.
The use of lectin KM+ allowed the detection of all pathologic landmarks of AD. Although the number of cases was small, there was a correlation between the two diagnostic approaches. We have currently obtained brains from demented patients having estimated clinical dementia ratings, which should permit further testing of the use of KM+ as a tool for AD diagnosis.
Supported by FAEPA, FAPESP and CAPES.
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