Longitudinal evaluation of serum MOG-IgG titers in MOGAD after initiation of maintenance immunoglobulin: A case series.

BACKGROUND: Myelin oligodendrocyte glycoprotein antibody-associated disease (MOGAD) is a distinct demyelinating disease of the central nervous system. Immunoglobulin (Ig) has been used as a maintenance therapy to prevent relapses in MOGAD, but the impact of Ig on serum MOG-IgG titers is unclear. OBJECTIVE: To characterize the variation in serum MOG-IgG titers after initiation of Ig treatment in people with MOGAD. METHODS: We conducted a retrospective study of 10 patients with a diagnosis of MOGAD and available serum MOG-IgG titers before and after initiation of maintenance Ig treatment. RESULTS: We found that most of the patients remained MOG-IgG seropositive while on Ig treatment with a reduced or unchanged titer, despite a lack of disease activity. CONCLUSIONS: This case series suggests that the mechanism of action of Ig therapy in MOGAD is not exclusively dependent on MOG-IgG titer reduction.