Objective:To explore the effect of carnosine on peripheral blood IFN-γ and IL-4 in rats with focal cerebral ischemia. Methods:Thirty male SD rats were randomly divided into 3 groups:the sham-operated group (n=10),the model group (n=10) and the carnosine-treated group(n=10). The rat model of the right middle cerebral artery occlusion (MCAO) was established by suture method in model group and the carnosine-treated group. After making the MCAO model,the rats in the carnosine-treated group were lavaged with soluble carnosine once a day at the doses of 1 g/(kg-d) as the criteria of their body mass,and the same volume of normal saline was lavaged in the sham operation and the model group. The neurological function was scored with Longa 5-point scale at postoperative 24 h and 72 h. The levels of IFN-γ and IL-4 in peripheral blood were detected by ELISA method at 24 h and 72 h. Brain tissues were obtained for HE staining at postoperative 72 h and observed by pathological histology. Results:Compared with the model group,there were significant differences in the neurological outcome scores in the carnosine-treated group at 24 h and 72 h (P < 0.05),There was a significant decrease at 24 h and 72 h of the carnosine-treated group (P < 0.05). At 24 h and 72 h,compared with the sham-operated group,the level of IFN-γ and IFN-γ/IL-4 ratio were significant decreased (P < 0.05). The level of IL-4 was significant increased (P < 0.05). After cerebral ischemia,neurons in cerebral cortex of rats were severe necrosis and the pathological injury of cerebral cortex in rats was obvious. After carnosine treatment,secondary neuron injury mitigated. Conclusion:Peripheral immune suppression exists in rats with focal cerebral ischemia. Carnosine could has potential protective effective on peripheral immune suppression of MCAO rats and the mechanism could be IFN-γ,IL-4 and IFN-γ/IL-4 ratio elevation.