Cover Story：Multiple sclerosis (MS), an autoimmune disease of the CNS with prominent demyelination and axonal degeneration, is more prevalent in women than men. EAE is a widely used animal model of MS for preclinical therapy development. In this report, a 29 days observation of the EAE model induced by MOG33-35 in C57BL/6 mice was performed. From the clinical course, we found no significant difference between male and female mice in the incidence and onset time, but males had a more serious disease score than that in females. And histological examination of spinal cord was performed at day 21 post-immunization. Compared with male mice, female mice had a dramatic increase of leukocyte infiltration in the spinal cord. Luxol fast blue staining also revealed enhanced demyelination in male mice compared to female mice. The CNS leukocyte infiltration was also quantified by flow cytometry analysis at day 19 post-immunization. The results again confirmed that the CD4 T cells accumulated in the CNS of EAE mice were increased in male mice. We further quantified the number of TH-1 and TH-17 cells in the CNS infiltrates and found that the absolute number of both TH-17 and TH-1 cells were significantly increased in male mice. Taken together, these data indicate that sex difference exists in EAE induced by MOG33-35 in C57BL/6 mice, and this will provided useful indications for further studies on the selection of animals in the EAE model.
