A surface plasmon resonance biosensor assay for measurement of anti-GM(1) antibodies in neuropathy

Objective: To develop a rapid assay for the detection and measurement of an ti-GM(1) ganglioside antibodies in patients with neuropathy, using a surfac e plasmon resonance-based biosensor. Background: Elevated levels of anti-GM (1) ganglioside antibodies are observed in patients with acute and chronic motor neuropathies. Assays for detecting anti-GM(1) antibodies in serum are increasingly being used to help the physician in the evaluation of these p atients. Methods: Antigens were immobilized by adsorption of GM(1) (active) and GM(2) (control) gangliosides onto a dextran-based sensor chip which is in contact with a flow cell carrying the sample. Interaction of specific a ntibodies directed against GM(1) with the ganglioside-coated sensor chip ca used a change in refractive index at the surface of the chip, which was det ected by an optical sensor, using the phenomenon of surface plasmon resonan ce. Sera from patients and healthy individuals were analyzed by the new ass ay and results were compared with those from ELISA. Anti-GM, antibody isoty pe was identified by using a secondary antibody. Results: The binding of an ti-GM(1) antibodies to the immobilized GM(1) was observed in real time afte r reference subtraction of the response from GM(2) control. The response wa s proportional to antibody concentration. The assay exhibited high specific ity for sera from patients with multifocal motor neuropathy and Guillain-Ba rre syndrome with antibodies against GM(1). Conclusions: The surface plasmo n resonance biosensor assay offers a rapid system for directly measuring an tibody levels in serum without the use of any labels, while comparing favor ably with the ELISA system in sensitivity and specificity.