Mostly separate distributions of CLAC- versus Abeta40- or thioflavin S-reactivities in senile plaques reveal two distinct subpopulations of beta-amyloid deposits

Am J Pathol. 2004 Jul;165(1):273-81. doi: 10.1016/s0002-9440(10)63295-6.


Collagenous Alzheimer amyloid plaque component (CLAC) is a unique non-Abeta amyloid component of senile plaques (SP) derived from a transmembrane collagen termed CLAC-precursor. Here we characterize the chronological and spatial relationship of CLAC with other features of SP amyloid in the brains of patients with Alzheimer's disease (AD), Down syndrome (DS), and of PSAPP transgenic mice. In AD and DS cerebral cortex, CLAC invariably colocalized with Abeta42 but often lacked Abeta40- or thioflavin S (thioS)-reactivities. Immunoelectron microscopy of CLAC-positive SP showed labeling of fibrils that are more loosely dispersed compared to typical amyloid fibrils in CLAC-negative SP. In DS cerebral cortex, diffuse plaques in young patients were negative for CLAC, whereas a subset of SP became CLAC-positive in patients aged 35 to 50 years, before the appearance of Abeta40. In DS cases over 50 years of age, Abeta40-positive SP dramatically increased, whereas CLAC burden remained at a constant level. In PSAPP transgenic mice, CLAC was positive in the diffuse Abeta deposits surrounding huge-cored plaques. Thus, CLAC and Abeta40 or thioS exhibit mostly separate distribution patterns in SP, suggesting that CLAC is a relatively early component of SP in human brains that may have inhibitory effects against the maturation of SP into beta-sheet-rich amyloid deposits.

Publication types

  • Case Reports
  • Comparative Study
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Adult
  • Aged
  • Aged, 80 and over
  • Alzheimer Disease / metabolism
  • Alzheimer Disease / pathology
  • Amyloid beta-Peptides / metabolism*
  • Animals
  • Antibodies, Monoclonal / metabolism
  • Benzothiazoles
  • Down Syndrome / metabolism
  • Down Syndrome / pathology
  • Female
  • Fluorescent Antibody Technique, Indirect
  • Humans
  • Immunohistochemistry
  • Male
  • Membrane Proteins / metabolism*
  • Membrane Proteins / ultrastructure
  • Mice
  • Mice, Transgenic
  • Middle Aged
  • Neocortex / cytology
  • Neocortex / metabolism
  • Neocortex / pathology
  • Neurons / metabolism
  • Neurons / pathology
  • Non-Fibrillar Collagens*
  • Peptide Fragments / metabolism*
  • Plaque, Amyloid / chemistry*
  • Plaque, Amyloid / ultrastructure
  • Thiazoles / metabolism*
  • Tissue Distribution


  • Amyloid beta-Peptides
  • Antibodies, Monoclonal
  • Benzothiazoles
  • COL25A1 protein, human
  • Membrane Proteins
  • Non-Fibrillar Collagens
  • Peptide Fragments
  • Thiazoles
  • amyloid beta-protein (1-42)
  • amyloid beta-protein (40-1)
  • thioflavin T