Development of a cell-based assay for the detection of anti-aquaporin 1 antibodies in neuromyelitis optica spectrum disorders.

OBJECTIVE: To develop a cell-based assay (CBA) to detect aquaporin 1 (AQP1) antibodies and determine sensitivity/specificity in patients with neuromyelitis optica (NMO) spectrum disorders. METHODS: A HEK-293T transfected cell model expressing AQP1 was established and detected to be serum AQP1 antibodies. RESULTS: AQP1 antibodies were present in 73/98 (74.5%) AQP4 antibody-positive patients. Some AQP4 antibody-negative patients were also AQP1 antibody-positive. Test sensitivity was 74.5% in 98 AQP4 antibody-positive patients. Test specificity was 79.6% in 67 multiple sclerosis (MS) patients and 31 controls. CONCLUSION: A sensitive and simple CBA was developed to detect serum AQP1 antibodies. AQP1 antibodies were mainly present in NMO and its high-risk syndrome, but also in some MS patients.