Distribution of apolipoprotein E in senile plaques in brains with Alzheimer's disease: Investigation with the confocal laser scan microscope

In order to elucidate the mechanism of the occurrence of apolipoprotein E(ApoE) in senile plaques (SP) in the brain of Alzheimer's disease (AD) patients, we morphologically examined double immunofluoresent-stained sections by scanning with the confocal laser scan microscope (LSM) and reconstructed their three-dimensional structure by a computerized imaging technique. Brain samples were obtained from six pathologically diagnosed AD patients, including patients with the genotype ApoE epsilon 3/3 and epsilon 4/4 ApoE genotype. We found some clear differences in distribution and shape in the staining patterns of plaque-shaped deposits by ApoE antibody and amyloid beta-protein (A beta) antibody. ApoE deposits were generally larger than A beta deposits in the same region and were distributed widely at the periphery of A beta deposits. Several A beta deposits of typical, compact and primitive plaques were often included in one diffuse plaque-like deposit of ApoE. Some ApoE deposits did not exhibit any A beta-immunoreactivity. Each core represented by ApoE and A beta did not show complete overlap. Typical plaques tended to be composed mainly of A beta-immunoreactivity and had little ApoE-immunoreactivity. The discrepancy between ApoE and A beta deposition may reflect different stages of amyloidogenesis in SP. The presence of ApoE alone in plaques may represent the pathological stage before the beginning of massive A beta deposition. (C) 1977 Elsevier Science B.V. All rights reserved.