Aquaporin-4 (AQP4) Autoantibody
Enzyme Immunoassay for the quantitative determination of autoantibodies to aquaporin-4 (AQP4) in serum
Characteristics
Reliable and convenient method to measure AQP4 autoantibodies, which are a specific marker for Neuromyelitis Optica (NMO), also known as Devic’s syndrome.
Measurement of AQP4 autoantibodies can be of considerable value in distinguishing NMO from Multiple Sclerosis when full clinical features may not be apparent and early intervention may prevent or delay disability. Total assay time is ~3 hours only. The ELISA method is an easy assay format for use in the routine clinical laboratory and suitable for automated systems.
The ELISA is manufactured under licence to US patent 7,101,679 and 7,947,254 and European patent 1700120 and related patents and patents pending in other countries.
The AQP4 autoantibody ELISA assay kit is intended for use by professional persons only, for the quantitative determination of AQP4 autoantibodies in human serum. Neuromyelitis optica (NMO), also known as Devic’s syndrome, is an immune-mediated neurologic disease that involves the spinal cord and optic nerves. It can be considered to be a disorder distinct from multiple sclerosis (MS). A serum immunoglobulin G autoantibody (NMO-IgG) has been shown to be a specific marker for NMO and the water channel aquaporin 4 (AQP4) has been identified as the antigen for NMO IgG. Measurement of AQP4 autoantibodies can be of considerable value in distinguishing NMO from MS when full clinical features may not be apparent and early intervention may prevent or delay disability.
In AQP4 autoantibody ELISA, AQP4 antibodies in patients’ sera, calibrators and controls are allowed to interact with AQP4 (M23 isoform) coated onto ELISA plate wells and liquid phase biotinylated AQP4. AQP4 antibodies bound to the AQP4 coated on the well will also interact with AQP4-Biotin due to the divalent nature of antibodies. After incubation at room temperature for 2 hours with shaking, the well contents are discarded, leaving AQP4-Biotin bound to the well via an AQP4 autoantibody bridge. The amount of AQP4-Biotin bound is then determined in a second incubation step involving addition of streptavidin peroxidase (SA-POD), which binds specifically to biotin. Excess, unbound streptavidin peroxidase is then washed away and addition of the peroxidase substrate 3,3’,5,5’- tetramethlybenzidine (TMB) results in formation of a blue colour. This reaction is stopped by the addition of a stop solution, causing the well contents to turn yellow. The absorbance of the yellow reaction mixture at 450nm and 405nm is then read using an ELISA plate reader. A higher absorbance indicates the presence of AQP4 autoantibody in the test sample. Reading at 405nm allows quantitation of high absorbances. Values below 10 U/ml should always be measured at 450nm. The measuring interval is 3.0 – 80 U/ml (arbitrary units).
Manufactured under licence to US patents 7,101,679 and 7,947,254, European patent 1700120, Chinese patent ZL200480040851.3, Japanese patent 4538464 and related patents and patents pending in other countries.
- Schulze F, Wesemann R, Schwedhelm E, Sydow K, Albsmeier J, Cooke JP, Böger RH.
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