CD81 and neuromyelitis optica: Consistent with the derivation of the sEVs obtained in this study, both NMO-EVs and MO-EVs contained endosome-associated proteins, including Rab GTPases (Rab11a), common metabolic enzymes (Eno1, Pkm, GAPDH), Heat shock proteins (HSP90ab1, HSPa1a), membrane transport proteins (Anxa2, Anxa4, Anxa5, Anxa6), cytoskeletal components (Acta1, Actb, Tuba1b, Tuba4a, Tubb5, Cfl1), membrane adhesion proteins (Itgb3, Itga2b), signal transduction protein kinases (Marcks, Pgk1), common proteins related to apoptosis (histones), anti-apoptotic proteins (Lgals1), and the tetraspanin protein CD81.