Feasibility Study of Anti-Neurofilament Antibodies Detection by Indirect Quenching Fluoroimmunoassay

Background: 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. Materials and Methods: 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. Results: 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. Conclusion: 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.