Figure 1

Optimization of a standard protocol for NMO diagnosis based on indirect immunofluorescence of cells expressing AQP4. The normal cell-based assay -using AQP4 as the antigen target in NMO-IgG detection- starts with culturing the cells and transfecting them with an AQP4 vector to achieve expression of the protein, before initiating the immunocytochemistry protocol itself. Then, standard procedures of fixation, permeabilization and blocking are performed before incubation with the primary and secondary antibodies, in a protocol that would take approximately 20 days. On the other hand, frozen cells overexpressing AQP4 can be stored, for a considerable time, at -80°C just after the blocking step, and be used for continuation of the immune protocol on receiving a patient’s serum, producing equivalent results in only 3 days.