Figure 1. Flowchart of the NMO cohort.
Of 163 patients whose serum was tested (one or more sequential specimens) by tissue-based IIF, 53 were scored negative. For 49 with available stored specimens, 30 (61%) were found to be AQP4-IgG positive when retested by recombinant antigen–based assays. AQP4 = aquaporin-4; CBA = cell-based assay; FACS = fluorescence-activated cell sorting assay; IgG = immunoglobulin G; IIF = indirect immunofluorescence; NMO = neuromyelitis optica; QNS = insufficient serum for further evaluation.