IL‐2mAb reduces demyelination after focal cerebral ischemia by suppressing CD8(+) T cells

AIMS: Demyelination, one of the major pathological changes of white matter injury, is closely related to T‐cell–mediated immune responses. Thus, we investigate the role of an IL‐2 monoclonal antibody (IL‐2mAb, JES6‐1) in combatting demyelination during the late phase of stroke. METHODS: IL‐2mAb or IgG isotype antibody (0.25 mg/kg) was injected intraperitoneally 2 and 48 hours after middle cerebral artery occlusion (MCAO) surgery. Infarct volume, peripheral immune cell infiltration, microglia activation, and myelin loss were measured by 2,3,5‐triphenyte trazoliumchloride staining, immunofluorescence staining, flow cytometry, and Western blot. Intraperitoneal CD8 neutralizing antibody (15 mg/kg) was injected 1 day before MCAO surgery to determine the role of CD8(+) T cells on demyelinating lesions. RESULTS: IL‐2mAb treatment reduced brain infarct volume, attenuated demyelination, and improved long‐term sensorimotor functions up to 28 days after dMCAO. Brain infiltration of CD8(+) T cells and peripheral activation of CD8(+) T cells were both attenuated in IL‐2 mAb‐treated mice. The protection of IL‐2mAb on demyelination was abolished in mice depleted of CD8(+) T cell 1 week after stroke. CONCLUSIONS: IL‐2mAb preserved white matter integrity and improved long‐term sensorimotor functions following cerebral ischemic injury. The activation and brain infiltration of CD8(+) T cells are detrimental for demyelination after stroke and may be the major target of IL‐2mAb posttreatment in the protection of white matter integrity after stroke.