M. Chen et al., PLATELETS ARE THE PRIMARY SOURCE OF AMYLOID BETA-PEPTIDE IN HUMAN BLOOD, Biochemical and biophysical research communications, 213(1), 1995, pp. 96-103
The main component of Alzheimer's disease (AD) amyloid deposits is amy
loid beta-peptide (A beta), a fragment of the larger amyloid precursor
protein (APP). The cellular source of A beta is not known, but a circ
ulatory origin has been postulated. We studied human blood from health
y individuals and found that platelets account for almost 90% of the t
otal anti-A beta immunoreactivity detected in whole blood. Using rever
se-phase HPLC, we identified a platelet peptide which corresponds to A
beta by three criteria. (a) it shares a retention time with the synth
etic A beta(1-40) peptide in two consecutive HPLC tests; (b) it intera
cts with two anti-A beta antibodies in separate ELISAs; and, (c) its p
artial N-terminal amino acid sequence closely matches that of A beta.
The detection of this peptide in platelets indicates that, aside from
the well-known non-amyloidogenic (secretory) pathway, the processing o
f APP in platelets from healthy individuals also involves an amyloidog
enic pathway. These findings are consistent with the view that platele
ts are one of the major sources of A beta in the circulation. (C) 1995
Academic Press, Inc.