Cerebrospinal Fluid IL-21 Levels in Neuromyelitis Optica and Multiple Sclerosis. Wu A, Zhong X, Wang H, Xu W, Cheng C, Dai Y, Bao J, Qiu W, Lu Z, Hu X Can J Neurol Sci. 2012 Nov; 39(6):813-20. PMID: 23041403. Abstract CommentRecommendBookmarkWatch