Ubiquitin in cerebrospinal fluid: a rapid competitive enzyme-linked immunoflow assay

The aims of this study were to develop a rapid immunoassay to determine the levels of ubiquitin in cerebrospinal fluid and to establish the ubiquitin levels in the spinal fluid of normal aged individuals. A competitive enzyme-linked immunoflow assay was developed. In this assay, ubiquitin is bound to nitrocellulose membrane, after which the primary antibody-test sample mixture and the enzyme-labeled secondary antibody under vacuum are applied sequentially. The final reaction product is collected in a microtiter plate by suction. This competitive assay requires only approximately 4 h and is potentially useful for determining in biological fluids the levels of any antigen or its antibodies that might be present. Employing this immunoassay, cerebrospinal fluid ubiquitin levels were found to be 147.5 +/- 5.2 ng ml-1 in non-neurological aged cases.