Inflammatory response after middle cerebral artery occlusion (MCAO) has been a focus of research recently, but the effect of inflammatory cells on ischemic neurons remains unclear. In order to study the effect of the inflammatory reaction on brain ischemic injury, we observed the morphology, number and distribution of CD3-, CD8-, ED1- and ED2-positive cells systematically in the caudate-putamen of rats in a MCAO model. The present results show that all four types of inflammatory cells first infiltrated the ischemic penumbra and then migrated into the center of the ischemic area, but the morphological changes and infiltration processes differed significantly; the infiltration of CD3- and CD8-positive cells into the ischemic area started at 3 days postischemia, and their number peaked at 1 week; however, although ED1- and ED2-positive cells were also observed at 3 days after ischemia, they reached their maximum number at 2 and 4 weeks, respectively. Moreover, ED1-and ED2-positive cells showed evident hyperplasia and hypertrophy in morphology. Our results also showed that the response of CD3-, CD8-, ED1- and ED2-positive cells in the ischemic area and the pathological changes in ischemic brain tissue could be inhibited by cyclosporine A. The results suggest that the infiltration and reaction of inflammatory cells are involved in the pathological process of ischemic brain injury.