[Detection of anti-aquaporin 4 antibody in neuromyelitis optical]

To assess the sensitivity and specificity of anti-aquaporin 4 antibody in the diagnosis of neuromyelitis optical (NMO) and analyze the relationship between clinical features and different NMO-IgG status.

A total of 269 serum specimens were collected from the patients with NMO, high-risk for NMO, multiple sclerosis (MS) and miscellaneous diseases and analyzed with HEK-293T cells transfected by aquaporin 4 cDNA. The sensitivity and specificity of anti-aquaporin 4 antibody in the diagnosis of NMO were calculated, Spearman correlation coefficients were used to examine the relationship between clinical features and antibody titer.

(1) The results of cell-based immunofluorescence assay showed 36 examples of 47 NMO patient serums (76.6%) were positive, 7/23 high-risk for NMO positive (30.4%), 3/85 multiple sclerosis (3.5%) positive, 1/48 miscellaneous neurological disorders (2.1%), 2/16 immune system diseases positive (12.5%) and negative in all 50 healthy serum specimens. Sensitivity and specificity were 76.6% and 97.0% for discriminating NMO from MS and other diseases. (2) Anti-AQP4 antibody titer had no obvious correlation to relapses, spinal lesion length and EDSS (P > 0.05). (3) Anti-AQP4 antibody titer became lower after a high dose of intravenous methylprednisolone (P < 0.05).

Anti-AQP4 antibody in NMO has a high specificity and sensitivity so as to contribute to early diagnosis and optimized treatment of NMO. And its titer decreases after a high dose of intravenous methylprednisolone. But there is no correlation between its titer and length of spinal cord lesions, relapsing frequency or expanded disability status scale (EDSS) score.