Humoral pattern II multiple sclerosis pathology not associated with neuromyelitis Optica IgG.

T he pathogenic relationship between neuromyelitis optica (NMO) and multiple sclerosis (MS) continues to be debated despite mounting evidence that these are distinct entities. The NMO-IgG, which targets the water channel protein aquaporin-4 (AQP4), is the first confirmed serum biomarker for any form of central nervous system inflammatory demyelinating disease and reliably distinguishes NMO from MS and other neurological diseases. Four immunopathological patterns (IP I-IV) have been described in early active MS lesions. Some investigators have interpreted humoral MS IP II as having an immunopathogenic link with NMO because both share complement and immunoglobulin deposition and have a greater likelihood than other forms of MS to respond favorably to plasma exchange therapy. Here, we describe the NMO-IgG status of a cohort of patients with biopsy-proven early active lesions consistent with MS.