Clinical features of Chinese patients with multiple sclerosis with aquaporin-4 antibodies in cerebrospinal fluid but not serum

The objective of this study was to determine the levels of aquaporin-4 (AQP4) antibodies in the cerebrospinal fluid (CSF) of patients meeting the diagnostic criteria for multiple sclerosis (MS) and to describe some of the clinical features of CSF-positive cases. Thirty-five patients fulfilling the diagnostic criteria for MS but not neuromyelitis optica were included in this study. AQP4 antibodies were detected using a cell-based assay. None of the serum samples were positive for AQP4 antibodies. Five CSF samples (14.3%, 5/35) were positive for AQP4 antibodies. All CSF-positive patients had atypical brain lesions in areas known to have high levels of AQP4 expression. CSF AQP4 antibody testing is an important diagnostic aid in patients meeting MS criteria but with atypical brain or spinal lesions and serum negative for AQP4 antibodies.