They have proposed that NMO patients have elevated CSF cytokines and chemokines associated with Th17 (IL-6, IL-8, and G-CSF), Th2 (IL-1, IL-10, and IL-13) and B cell axes (CXCL13 and IL-21), which contrasts with MS, which is mainly a Th1-dominant disease [129]. Here, IL21 is linked to neuromyelitis optica.