Fig. 2. In-house CBA to detect AQP4-IgG in patient sera. Sera from healthy subjects (A-D), MS patients (E-H), and NMOSD patients (I-L) were added to AQP4-GFP-transfected HEK293 cells. HEK293 cells transfected with AQP4-GFP show green fluorescence in the cytosol under fluorescence microscopy (B, F, and J). When the patient serum contained AQP4-IgG, red fluorescence was detected on the HEK293 cell membrane (K) due to binding of AQ4-IgG to AQP4, which is expressed on the membrane of HEK293 cells. AQP4-IgG: aquaporin 4-IgG, CBA: cell based assay, GFP: green fluorescent protein, HEK293: human embryonic kidney 293, MS: multiple sclerosis, NMOSD: neuromyelitis optica spectrum disorder.
