Tregs are present in the ischemic brain early after stroke and are mainly found in the vascular compartment. (A) Flow cytometric analysis of FoxP3⁺ Tregs counted in the ischemic hemispheres on day 1 (d1) and d3 after 60 minutes of tMCAO or sham-operated mice. Transcardial perfusion of animals was omitted before brain sampling. (B) Top panel is a macroscopic view of a representative TTC-stained brain section from a regular DEREG mouse without diphtheria toxin treatment on day 1 after 60 minutes of tMCAO showing that the immunohistochemical pictures shown at the bottom of the figure were taken from the basal ganglia (BG). Bottom panel is immunohistochemical brain sections from DEREG mice on day 1 after 60 minutes of tMCAO showing FoxP3⁺ Tregs predominantly in the cerebral vasculature (double staining with the endothelial marker CD31). The area of the basal ganglia is depicted. C indicates cortex. *P < .05; ***P < .0001.