Boster Bio

What is AQP4 antibody?

AQP4 antibody (aquaporin-4 antibody) also known as NMO-IgG is a highly sensitive and specific serological marker of Neuromyelitis Optica. Neuromyelitis Optica (NMO) is a severe central nervous system (CNS) inflammatory condition with a possible autoimmune origin that mostly affects the optic nerves and spinal cord. Neuromyelitis optica (NMO) and a related spectrum of inflammatory CNS disorders are unified by detection of a serum autoantibody specific for the aquaporin-4 (AQP4 antibody)

The water channel protein aquaporin 4 (AQP4) is located on astrocytes, which surround the blood-brain barrier (a layer of cells responsible for preventing dangerous substances in the blood from crossing into the brain). The blood-brain barrier is thought to allow AQP4 antibodies to penetrate the central nervous system.

Human AQP4 has at least two isoforms. It has recently been proposed that the shorter M23 isoform may be preferred in terms of test sensitivity. It has been suggested that AQP4-IgG may target epitopes produced during M23-AQP4 synthesis to so-called orthogonal arrays of particles (OAPs). In fact, AQP4-IgG binding affinity to M23-AQP4 was found to be higher than M1-AQP4 in a recent study.

The discovery of aquaporin-4 antibodies allows for an accurate diagnosis of NMOSD and eliminates the possibility of a misdiagnosis as multiple sclerosis. When patients arrive with NMOSD, around 90% of them are misdiagnosed as having Multiple Sclerosis.