Clinical Diagnosis of Myelin Oligodendrocyte Glycoprotein Antibodies Based on CHO Flow Cytometry Live Cell-based Assay

Background In this study, two cell lines, CHO and HEK293, which overexpress the full-length protein of MOG, were used to evaluate the diagnostic performance of the two cell lines in the detection of serum MOG antibodies in patients with MOGAD (MOG Antibody Disease) under different titers and CBA method. Methods Sera were collected from 36 suspected patients with clinical manifestations of MOGAD but not yet subjected to antibody assay, and the collected sera were subjected to CBA-IF (cell-based assay-immunofluorescence) and CBA-FC (cell-based assay-flow cytometry) using two cell lines, CHO and HEK293, which overexpressed MOG. Five different dilutions (1:10, 1:32, 1:100, 1:320, and 1:640) were used for both CBA-IF and CBA-FC methods for sensitivity and consistency testing. X2 test was used for gender and age. Results MOG-IgG was detected in the sera of 30 patients consistent with the clinical manifestations of multiple sclerosis, autoimmune encephalomyelitis, and optic neuromyelitis, and serum MOG-IgG was detected as a negative result in another 6 patients, including two patients who tested positive for antibody to aquaporin-4 (AQP4-IgG) and negative for MOG-IgG. The results of CBA-FC and CBA-IF results had 84% concordance and the CBA-IF titers obtained by endpoint dilution correlated with the CBA-FC titers. The highest serum dilution resulted in increased CBA-FC sensitivity but decreased specificity. Conclusion The present study demonstrated that the sensitivity of CBA-FC detection of MOG antibody using CHO cell line at antibody titer of 1:100 was higher than using 293 cell line. CHO cell line is thus expected to be further applied in the clinic. In contrast, CBA-FC has a slight advantage over CBA-IF in the detection of MOG antibodies in certain titers and can be used as a diagnostic technique for MOG-IgG in clinical practice. In addition, the combination of the two techniques can be used as a tool to differentiate non-specific binding and to overcome the limitations of a single assay in certain specific situations.