Amyloid beta protein 1-40 and 1-42 levels in matched cerebrospinal fluid and plasma from patients with Alzheimer disease

We quantitated amyloid beta proteins 1-40 (A beta 40) and 1-42 (A beta 42), and alpha1-antichymotrypsin (ACT) in matched cerebrospinal fluid (CSF) and plasma of 50 patients with probable Alzheimer disease, and analyzed the re lationships with age, sex, Mini-Mental State Examination (MMSE), and apolip oprotein E phenotype. There was no relation between CSF A beta 40 and A bet a 42 levels with those of plasma. CSF and plasma A beta 40 and A beta 42 le vels showed no association with age, sex, and MMSE score. There was a signi ficant correlation between CSF ACT and plasma ACT levels. The data suggest that plasma ACT crosses the blood-brain barrier. However, a lack of correla tion between CSF A beta 40 and A beta 42 levels with those of plasma sugges ts that A beta in CSF and plasma originates from different sources. (C) 200 1 Elsevier Science Ireland Ltd. All rights reserved.