IL-17A is expressed by CD3⁺ T cells in human brain tissue shortly after stroke. H&E staining of unaffected brain tissue (A) and ischemic brain tissue 24 hours after stroke (B). The ischemic tissue was further analyzed by immunohistochemistry for the presence of neutrophils (MPO; C); T lymphocytes (CD3; D); γδ T cells (E), and IL-17A (F). (G) Double immunofluorescence analysis of CD3 (red) and IL-17A (green) at higher magnification. Scale bars = 50 μm (A-F) and 10 μm (G).