A recent study found that the circulating memory Tfh cells (ICOS+, CCR7−, CCR7−, ICOS+, CCR7+, and CCR7+ICOS+ Tfh cells) and serum and cerebrospinal fluid IL-21 levels in patients with NMO/NMOSD significantly increased (7). This evidence concerns the gene CCR7 and neuromyelitis optica.