Presence of anti-Ro/SSA antibody may be associated with anti-aquaporin-4 antibody positivity in neuromyelitis optica spectrum disorder.

Background: Neuromyelitis optica (NMO) is often associated with systemic autoimmune diseases or serological markers of non-organ-specific autoimmunity, and has been most frequently associated with Sjögren's syndrome and anti-Ro/SSA antibody (SSA-Ab) positivity in Asian populations.

Objective: We evaluated the clinical significance of anti-Ro/SSA antibody positivity in patients with NMO spectrum disorder (NMOSD).

Methods: We retrospectively collected data from 106 consecutive patients with NMOSD and reviewed clinical features and laboratory findings. All patients underwent tests for SSA-Ab and anti-aquaporin-4 antibody (AQP4-Ab) using cell-based indirect immunofluorescence assays.

Results: Among 106 patients, 20 (18.9%) were positive for SSA-Ab. Of 48 AQP4-Ab-positive patients, 18 (37.5%) had SSA-Ab. AQP4-Ab seropositivity was 90.0% in patients positive for SSA-Ab, and 32.6% in patients without SSA-Ab (p<0.001). Presence of SSA-Ab was associated with systemic autoimmune diseases, including Sjögren's syndrome (p<0.001) and systemic lupus erythematosus (p=0.003), and with the presence of non-organ-specific autoantibodies such as anti-nuclear antibody and anti-dsDNA antibody in patients with NMOSD, but was not associated with annualized relapse rate or final Expanded Disability Status Scale score independent of AQP4-Ab positivity.

Conclusion: We found that the presence of SSA-Ab was highly associated with seropositivity for AQP4-Ab in patients with NMOSD.