Feasibility study of anti-neurofilament antibodies detection by indirect quenching fluoroimmunoassay

ABSTRACT

Neurofilaments [NFs] are the main constitutes of intermediate filaments in neurons. They are composed of three subunits with heavey, medium and low molecular weight. Anti-neurofilament antibodies exist in serum of patients with some neurodegenerative diseases. A fluoroimmunoassay has been developed for determining of antibodies against neurofilaments, using an anti-fluorescein serum and fluorescein-labeled NFs. Antibodies raised against bovine spinal cord NFs in rabbit and the labeled NFs are incubated with anti-fluorescein serum at room temperature. At high levels, binding of anti-neurofilaments [anti-NFs] to labeled NFs prevented subsequent binding of the anti-fluorescein to fluorescein groups, resulting in little change in the signals of the label. Conversely, at low level of anti-NFs the free fraction of the labeled NFs is available to be bound by anti-fluorescein, which markedly reduced fluorescence intensity of label. Thus, the fluorescence intensity of assay mixture directly reflects the amount of anti-NFs antibodies in the serum. It is concluded that the availability of fluorescein-labeled NFs and antibody directed against fluorescein group permit measurement of anti-NFs antibodies in serum of neurodegenerative patients