CONCENTRATION OF SERUM AMYLOID-P COMPONENT IN THE CSF AS A POSSIBLE MARKER OF CEREBRAL AMYLOID DEPOSITS IN ALZHEIMERS-DISEASE

Serum amyloid P component (SAP) is a normal plasma protein produced in the liver and co-deposited with amyloid fibrils in all types of amyloidosis, including cerebral beta-protein amyloid deposits associated with Alzheimer's disease (AD). We have measured its concentration and those of alpha(2)-macroglobulin, IgG and albumin in the CSF of 51 patients with AD and 50 healthy and disease control subjects. The mean levels of SAP were 12.8 ng/ml in AD and 8.5 ng/ml in controls (P<0.0125); there was no difference in the levels of the other proteins studied. The observed concentrations of SAP were much lower than expected for a protein of molecular weight 254620. The difference between AD and controls suggests that the concentration of SAP in the CSF may be affected by the presence of cerebral amyloidosis. (C) 1994 Academic Press, Inc.