Detection of Proteins in Normal and Alzheimer's Disease Cerebrospinal Fluid with a Sensitive Sandwich Enzyme-Linked Immunosorbent Assay


  • The present address of Dr. M. Mercken is Laboratory for Molecular Neuroscience and Aging Research, Mailman Research Center, McLean Hospital, Harvard Medical School, Belmont, MA 02178, U.S.A.

Address correspondence and reprint requests to Dr. P. Cras at Laboratory of Neurobiology, Born-Bunge Foundation, University of Antwerp, UIA BIdg. T, Universiteitsplein 1, B-2610 Wilrijk, Belgium.


Abstract— Alzheimer's disease is a progressive degenerative dementia characterized by the abundant presence of neurofibrillary tangles in neurons. This study was designed to test whether the microtubule-associated protein, a major component of neurofibrillary tangles, could be detected in CSF. Additionally, we investigated whether CSF levels were abnormal in Alzheimer's disease as compared with a large group of control patients. We developed a sensitive sandwich enzyme-linked immunosorbent assay using AT120, a monoclonal antibody directed to human, as a capturing antibody. With this technique, the detection limit for was less than 5 pg/ml of CSF. Using ATS, which recognizes abnormally phosphorylated ser-ines 199–202 in, the detection limit was below 20 pg/ml of CSF. However, with AT8, we found no immunoreactiv-ity in CSF, suggesting that only a small fraction of CSF contains the abnormally phosphorylated AT8 epitope. Our results indicate that CSF levels are significantly increased in Alzheimer's disease. Also, CSF levels in a large group of patients with a diversity of neurological diseases showed overlap with CSF levels in Alzheimer's disease.