查看文章

The main component of Alzheimer′s disease (AD) amyloid deposits is amyloid β-peptide (Aβ), a fragment of the larger amyloid precursor protein (APP). The cellular source of Aβ is not known, but a circulatory origin has been postulated. We studied human blood from healthy individuals and found that platelets account for almost 90% of the total anti-Aβ immunoreactivity detected in whole blood. Using reverse-phase HPLC, we identified a platelet peptide which corresponds to Aβ by three criteria. (a) it shares a retention time with the synthetic Aβ_1-40 peptide in two consecutive HPLC tests; (b) it interacts with two anti-Aβ antibodies in separate ELISAs; and, (c) its partial N-terminal amino acid sequence closely matches that of Aβ. The detection of this peptide in platelets indicates that, aside from the well-known non-amyloidogenic (secretory) pathway, the processing of APP in platelets from healthy individuals also …