Amyloid β 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 relationships with age, sex, Mini-Mental State Examination (MMSE), and apolipoprotein E phenotype. There was no relation between CSF A beta 40 and A beta 42 levels with those of plasma. CSF and plasma A beta 40 and A beta 42 levels showed no association with age, sex, and MMSE score. There was a significant correlation between CSF ACT and plasma ACT levels. The data suggest that plasma ACT crosses the blood-brain barrier. However, a lack of correlation between CSF A beta 40 and A beta 42 levels with those of plasma suggests that A beta in CSF and plasma originates from different sources. (C) 2001 Elsevier Science Ireland Ltd. All rights reserved.