Cell-based Assay And Related Titre Test For Aquaporin-4 Antibodies In Neuromyelitis Optica Of Chinese Populations

Introduction: The detection of aquaporin-4(AQP4) antibody is needed during the diagnosis of the disease according to the new standard since AQP4 antibody is involved in the pathogenesis of NMO. So far, there has been no large-scale study on anti-AQP4 antibody in NMO and related disorders in China yet. Objective: To develop an effective method to detect NMO-biomarker in Chinese population.Methods: We established human cell lines that express human AQP4 and used these cells to detect anti-AQP4 antibody in 184 sera of patients with NMO and four groups of other neurological disorders.Results: We found antibodies to AQP4 in 31 of 35 patients with NMO (88.6%) and in 6 of 14 patients with high risk syndromes of NMO (42.9%). However, none of the samples of the other three groups is positive. The extent of visual impairment and severity of brain and spinal cord injuries on MRI were positively correlated with anti-AQP4 antibody titres. Higher anti-AQP4 antibody titres were associated with the longer length of spinal cord lesions on MRI. Meanwhile, Anti-AQP4 antibody titres became lower after high-dose immunosuppressive agents. Conclusion: We firstly established a cell-based assay for AQP4 antibody in NMO of Chinese population. The AQP4-transfected cell-based assay appeared more sensitive than the previous assay, and it could be a powerful tool for the early diagnosis of NMO which is imperative for early therapeutic interventions.