A surface plasmon resonance biosensor assay for measurement of anti-GM1 antibodies in neuropathy

Abstract

Objective: To develop a rapid assay for the detection and measurement of anti-GM1 ganglioside antibodies in patients with neuropathy, using a surface plasmon resonance–based biosensor.Background: Elevated levels of anti-GM1 ganglioside antibodies are observed in patients with acute and chronic motor neuropathies. Assays for detecting anti-GM1 antibodies in serum are increasingly being used to help the physician in the evaluation of these patients.Methods: Antigens were immobilized by adsorption of GM1 (active) and GM2 (control) gangliosides onto a dextran-based sensor chip which is in contact with a flow cell carrying the sample. Interaction of specific antibodies directed against GM1 with the ganglioside-coated sensor chip caused a change in refractive index at the surface of the chip, which was detected by an optical sensor, using the phenomenon of surface plasmon resonance. Sera from patients and healthy individuals were analyzed by the new assay and results were compared with those from ELISA. Anti-GM1 antibody isotype was identified by using a secondary antibody.Results: The binding of anti-GM1 antibodies to the immobilized GM1 was observed in real time after reference subtraction of the response from GM2 control. The response was proportional to antibody concentration. The assay exhibited high specificity for sera from patients with multifocal motor neuropathy and Guillain–Barré syndrome with antibodies against GM1.Conclusions: The surface plasmon resonance biosensor assay offers a rapid system for directly measuring antibody levels in serum without the use of any labels, while comparing favorably with the ELISA system in sensitivity and specificity.