Reduced dosage rituximab in the treatment of anti-N-methyl-d-aspartate receptor encephalitis: An observation study in Chinese patients

The aim of this study was to observe the treatment effect and investigate the possible mechanism of reduced dosage (600 mg) rituximab treatment on anti-N-methyl-d-aspartate receptor (anti-NMDAR) encephalitis. The median modified Rankin Scale of ten enrolled patients decreased from 4 (range 2-4) before rituximab infusion to 0 (range 0-2) after a mean follow-up time of 24.3 ± 8.7 months. One patient relapsed 9 months after treatment. No severe adverse event was observed. The proportion of total B cells in lymphocytes was depleted from 13.4 ± 6.7% to 0.6 ± 0.8% one day after treatment. B cells started to regeneration at 3 months and reached 9.4 ± 3.7% at 12 months after treatment. At this time point, proportion of regulatory B cells (Breg) in reconstituted B cells was significantly higher than that before treatment (15.3 ± 12.1% vs. 0.5 ± 0.6%, p = 0.006), while proportion of memory B cells (Bmem) was significantly lower than baseline level (8.0 ± 4.5% vs. 30.2 ± 12.6%, p < 0.001). Our results supported that reduced dosage rituximab was effective and safe in treating anti-NMDAR encephalitis. B cell depletion and rebalance of Breg and Bmem might be involved in the treatment mechanism of this therapy.