ObjectiveTo test the hypothesis that the pattern of serum biomarkers of disease activity and disability in myelin oligodendrocyte glycoprotein antibody–associated disease (MOGAD) will be different from those in neuromyelitis optica spectrum disorder (NMOSD) with anti–aquaporin-4 antibodies (AQP4-Abs).MethodsUsing ultrasensitive single-molecule array assays, we measured neurofilament light chain (NfL), glial fibrillary acidic protein (GFAP), and tau in the sera of consecutive patients with MOGAD (n = 16) and NMOSD with AQP4-Ab (n = 33). Serum biomarker levels were compared between patients in relapse and remission states, and correlations between the levels of these biomarkers and Expanded Disability Status Scale (EDSS) scores were analyzed within each group.ResultsIn the MOGAD group, the serum tau level was higher in a relapse state than in a remission state (relapse vs remission: 0.5 [0.4–0.5] vs 0.2 [0.1–0.3] pg/mL, p = 0.027). Both serum levels of NfL and tau correlated with the EDSS score (NfL: r = 0.684, p = 0.003; tau: r = 0.524, p = 0.045). Meanwhile, in the NMOSD group, serum NfL and GFAP levels were higher in a relapse state than in a remission state (relapse vs remission: NfL, 34.8 [12.2–62.3] vs 13.0 [11.3–20.0] pg/mL, p = 0.010; GFAP, 253.8 [150.6–303.0] vs 104.4 [93.9–127.9] pg/mL, p = 0.016). Only the serum GFAP level correlated with the EDSS score (r = 0.485, p = 0.012).ConclusionThe pattern of serum biomarkers of disease activity and disability in MOGAD showed a distinct feature from those in NMOSD with AQP4-Ab, which implicates different pathogeneses between the 2 diseases.

To identify factors associated with plasma exchange response in neuromyelitis optica (NMO) spectrum disorders, the clinical and magnetic resonance imaging (MRI) features of 31 NMO-IgG-positive patients receiving plasma exchange for steroid-resistant exacerbations were analyzed. Functional improvement was observed in 65% of the patients. A lower baseline Expanded Disability Status Scale score was associated with favorable response (p = 0.040). Patients without cord atrophy had a higher success rate than patients with atrophy (p = 0.016). Levels of NMO-IgG did not differ between responders and non-responders before and after plasma exchange. In conclusion, a minimal pre-existing disability is the primary determinant of the effectiveness of plasma exchange.