A More Sensitive Radioimmunoassay for Neuron‐Specific Enolase Suitable for Cerebrospinal Fluid Determinations

Abstract

Neuron-specific enolase (NSE) and non-neuronal enolase (NNE) are highly specific neuronal and glial products, respectively, and are useful as biochemical markers of the 2 major cell types in the vertebrate CNS. An iodinated radioimmunoassay (RIA) procedure for human NSE (NSE-H) with approximately 50-fold greater sensitivity than the previously available tritiated assay is described. This assay is capable of detecting 100 pg of NSE-H per assay. NSE levels in human CSF which were previously undetectable with the tritiated RIA are now easily measured and are approximately 2 ng/ml of CSF. Results obtained with the newly described assay procedure on more concentrated brain tissue extracts are comparable to the tritiated RIA. The iodinated NSE RIA is capable of accurately detecting added amounts of NSE in human CSF, indicating the potential clinical usefulness of this assay in determining elevated levels of NSE in CSF.