【Objective】 This study was aimed to investigate the titer consistency in parallel between tissue-based IIFA and cell-based IIFA in Chinese patients with neuromyelitis optica (NMO) spectrum disorders. 【Methods】 Every sample was tested by the tissue-based IIFA and cell-based IIFA separately. Positive serum samples were titrated in doubling dilutions

to ascertain the maximum dilution that yielded positive results separately. We assessed the seroprevalence and the titer consistency of anti-aquaporin-4 antibodies of serum samples from patients with neuromyelitis optica (NMO

19)

recurrent optic neuritis (RON

17)

longitudinally extensive transverse myelitis (LETM

13)

multiple sclerosis (MS

31)

health control (HC

30). Moreover

we analyzed the relation of anti-aquaporin-4 antibody titers and spinal cord lesions on MRI. 【Results】 We noticed lack of concordance in titer detection in most samples between the two techniques. We found 63.2% (12/19) of NMO patients were seropositive for AQP4 antibodies by tissue-based IIFA versus 89.5% (17/19) by cell-based IIFA. 47.1% (8/17) of RON patients were seropositive for AQP4 antibodies by tissue-based IIFA versus 70.6% (12/17) by cell-based IIFA. 46.2% (6/13)of LETM patients were seropositive for AQP4 antibodies by tissue-based IIFA versus 69.2% (9/13) by cell-based IIFA. 6.5% (2/31) of MS patients were seropositive for AQP4 antibodies by tissue-based IIFA versus 9.7% (3/31) by cell-based IIFA. The lengths of spinal cord lesions on MRI were not correlated with the titers of anti-AQP4 antibody in both assays. The two assays have no linear dependence in measuring this antibody titer. 【Conclusion】 The current discrepancy between the two assays implies the necessity to study the potential impact on titers in both assays.