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 amylo idosis, including cerebral beta-protein amyloid deposits associated wi th Alzheimer's disease (AD). We have measured its concentration and th ose of alpha(2)-macroglobulin, IgG and albumin in the CSF of 51 patien ts with AD and 50 healthy and disease control subjects. The mean level s of SAP were 12.8 ng/ml in AD and 8.5 ng/ml in controls (P<0.0125); t here was no difference in the levels of the other proteins studied. Th e observed concentrations of SAP were much lower than expected for a p rotein of molecular weight 254620. The difference between AD and contr ols suggests that the concentration of SAP in the CSF may be affected by the presence of cerebral amyloidosis. (C) 1994 Academic Press, Inc.