CXCL13 and neuromyelitis optica: CSF CXCL13 levels are correlated with Expanded Disability Status Scale scores, annualized relapse rates (ARR), CSF white blood cells counts, and other measures in NMO and MS (Alvarez et al., 2013; Zhong et al., 2011), and serum CXCL13 levels are correlated with remission extent and magnetic resonance imaging activity during the first and second years, but not with interferon‐β1b or glatiramer acetate levels in MS patients (Festa et al., 2009).