NMO-IgG and Devic's neuromyelitis optica:: a French experience

Background A serum autoantibody biomarker, NMO-IgG has been recently described in patients with Devic's neuromyelitis optica (DNMO) and so called 'high-risk' patients for this disease. Our objectives were to replicate the test and to assess its usefulness. Methods Indirect immunofluorescence with a substrate of adult rat cerebellum and midbrain was used to identify the distinctive NMO-IgG staining pattern. We tested masked sera from 26 patients with DNMO (group 1), 21 patients with idiopathic acute transverse myelitis (ATM) (group 2), 21 patients with bilateral and/or recurrent idiopathic optic neuritis (group 3), 52 patients with classical multiple sclerosis (MS) (group 4), 36 patients with HTLV-1 infection (group 5) and 7 patients with miscellaneous disorders (group 6). Results We identified a vascular staining pattern typical of NMO-IgG. This particular staining was observed in 14/26 samples in group 1, 7121 in group 2 (positive only in longitudinally extensive acute transverse myelitis: 7113), 4121 in group 3 (with bilateral loss of vision in all seropositive cases), 5/52 in group 4 (none of them suggestive of DNMO), 0/36 in group 5 and 017 in group 6. Sensitivity of the test was 54% considering detection of DNMO (group 1), and specificity was respectively 94% and 90% when considering groups 4, 5 and 6 altogether or group 4 of MS patients only. Conclusion Detection of NMO-IgG is contributory to the distinction of DNMO and 'DNMO high-risk' syndromes from MS. This test may allow earlier diagnosis and help therapeutic decisions.