【Objective】 To investigate the performance of AQP4 isoform to detect AQP4 antibodies in neuromyelitis optica(NMO) patient’s sera. 【Methods】 We tested 205 masked serum samples from 40 NMO patients

39 longitudinally extensive transverse myelitis (LETM) patients

39 patients with recurrent optic neuritis (rON)

47 patients with multiple sclerosis (MS) and 40 healthy controls with the indirect immunofluorescence with a composite substrate of HEK293/pcDNA3.1(+)-M23-AQP4

HEK293/pcDNA3.1(+)-M1-AQP4

HEK293/pEGFP-N3-M23-AQP4

HEK293/pEGFP-N3-M1- AQP4. 【Results】 We found antibody to AQP4 was present in NMO spectrums. M23-AQP4 was more sensitivity than the M1-AQP4 and while the enhanced green fluorescent protein (EGFP) which was a tag protein may be interfere with the combination between the AQP4 antibody and AQP4. 【Conclusion】 M23-AQP4 appears to have a higher sensitivity than the M1-AQP4. It is expected to be a first consideration for the detection AQP4 antibody with the cell based assay.