Neuromyelitis optica immunoglobulins as a marker of disease activity and response to therapy in patients with neuromyelitis optica

Objective To determine whether neuromyelitis optica (NMO) immunoglobulin (IgG) antibody status in NMO/Devic's disease patients followed prospectively is persistent or can change relative to the clinical status and/or response to therapy. Design A cross-sectional group of patients with NMO, relapsing extensive longitudinal transverse myelitis (RLETM) or optico-spinal multiple sclerosis (OSMS) were evaluated for the presence of NMO IgG antibodies. Repeated evaluation was made in all NMO/RLETM patients and in a subgroup of OSMS patients. Setting Baird Multiple Sclerosis Center, Buffalo, New York, an academic multiple sclerosis center. Results Out of a consecutive cohort of 38 patients evaluated for the presence of NMO IgG, 12 had NMO and 26 had OSMS. Five of the 12 NMO/RLETM patients were NMO IgG positive at the time of their initial evaluation. Four of these patients were repeatedly tested for NMO IgG: two of these became negative and two remained positive. One patient who was initially negative became positive during an acute event and again became negative during the stable disease phase following treatment. A positive test result was associated with active disease, whereas a negative NMO IgG result was consistently found in stable, long-term treated patients. None of the OSMS patients were positive for NMO IgG even during acute attacks. Conclusions NMO IgG antibodies are associated with active NMO/RLETM. A well-controlled stable disease usually under effective immunosuppressive therapy can transform the NMO IgG to a negative status. Repeated NMO IgG testing should be considered as a useful biological marker for monitoring NMO/RLETM disease and or response to therapy.