Researchers using an assay developed by Sibia Inc. have founddecreased levels of the precursor protein to amyloid in thebrain and spinal fluid of people diagnosed as havingAlzheimer's disease.

The findings suggest a route to clinical diagnosis of the disease,the scientists reported today in the Proceedings of the NationalAcademy of Sciences.

The scientists from the University of California, Irvine, andtheir colleagues at the Free University Hospital in Amsterdam,the Netherlands, said the finding reflects the abnormalprocessing of the protein that is believed to generate amyloid,which forms the brain deposits implicated in the disease.

The findings have been confirmed in patients diagnosed withAlzheimer's who have died and in patients with mutations inthe genes coding for the precursor protein, according to theresearch that was to be presented today at the KeystoneSymposium on Neurodegenerative Disorders in Big Sky, Mont.

Previous examinations of the cerebrospinal fluid (CSF), theserum-like liquid that bathes the brain and spinal cord, haveshown conflicting results, some reporting higher, some slightlydecreased levels of the amyloid precursor protein (APP).

The Sibia assay used a highly specific and sensitive monoclonalantibody that was prepared to recognize purified human APP.Other studies had used antibodies prepared against syntheticpeptides or expressed peptides corresponding to variousportions of APP.

Mean levels of APP were about 3.5 times lower in 13 livingpatients diagnosed with probable Alzheimer's, compared with18 patients with non-Alzheimer's dementias and 16 healthysubjects.

"These findings suggest that abnormal metabolism of APP isreflected in the extracellular fluids of the central nervoussystem, and that CSF levels of soluble APP provide a usefulbiochemical marker to assist in the clinical diagnosis" of thedisease, the scientists concluded in the PNAS report.

Sibia is a privately held biotechnology company in San Diego,founded in 1981 by the Salk Institute for Biological Studies."We have completed most of the (testing) necessary to validatethe assay," Dr. William Comer, president and CEO, told BioWorld.Sibia is working with potential partners to format the assay foruse in clinical labs, he said.

UC Irvine has filed for a patent on the antibody, and Sibia haslicensed the technology, Comer said.

-- Roberta Friedman, Ph.D. Special to BioWorld

(c) 1997 American Health Consultants. All rights reserved.