Experimental allergic encephalomyelitis is a mouse model of human multiple sclerosis with similar pathology and pathogenesis. Th1 cells play an important role in the pathogenesis of experimental allergic encephalomyelitis. Therefore, Qun Xue, Fanli Dong and co-workers from the First Affiliated Hospital of Soochow University in China speculated that programmed cell death 1 ligand 1 (PD-L1) plays an important role in the pathogenesis of multiple sclerosis. A recent study by these researchers published in the Neural Regeneration Research (Vol. 8, No. 35, 2013) found that the expression of PD-L1 in the spinal cord and splenocytes of mice with experimental allergic encephalomyelitis was significantly increased compared with normal mice. This evidence provides the basement for exploring the role of PD-L1 in multiple sclerosis.