To determine whether B cell-depletion therapy (BCDT) with rituximab (RTX) reconfigures remission-phase immune networks in aquaporin-4 immunoglobulin G (AQP4-IgG)–positive neuromyelitis optica spectrum disorder (NMOSD), compared with conventional immunosuppression using azathioprine (AZA).

BCDT effectively reduces relapses in NMOSD, yet how it reshapes the immune landscape during remission remains uncertain.

We retrospectively analyzed a prospective NMOSD cohort at Asan Medical Center (June 2020–January 2023). Patients in remission provided longitudinal blood samples collected ≥3 months after the last infusion (three per patient). Twenty-eight AQP4-IgG? patients were included: 14 receiving RTX and 14 age-matched on AZA, yielding 81 remission-phase samples. Peripheral immune subsets were profiled by multiparameter flow cytometry, and 12 plasma cytokines were quantified. Between-group comparisons, cytokine–cell correlation networks, Expanded Disability Status Scale (EDSS) associations, and longitudinal trends with RTX were evaluated.

RTX treatment was associated with a skewed regulatory immune profile. The B cell compartment was dominated by transitional and naïve subsets (p <0.001), accompanied by contraction of memory pools. In the RTX group, TIGIT?CD226⁻ memory Tregs were enriched and NKT-like cells were consistently reduced compared with AZA, with stable overall Treg and CD4?/CD8? frequencies. Cytokine–cell networks also differed substantially. The AZA group showed dense B cell and NKT-like coupling with multiple pro-inflammatory cytokines (IL-1β, IL-2, IL-13, IL-17A, TNF-α), whereas the RTX group displayed a sparser, less inflammation-prone organization. Clinical associations also diverged: in RTX, EDSS correlated with soluble mediators (IL-6, TNF-α, IP-10) but not immune cell subsets, while in AZA, EDSS correlated positively with TIGIT? Tregs.