AQP4 and systemic lupus erythematosus: In Závada et al. study [15], sera of 76 patients with SLE and neurological symptoms, 50 of whom met the ACR nomenclature for NPSLE, were tested for AQP4-Ab in an indirect immunofluorescence assay employing HEK293 cells transfected with recombinant human AQP4.