PRF1 and Stroke: Moreover, brain-infiltrating CD8+ T lymphocytes of perioperative stroke mice responded with more Perforin (t(8) = 2.481, P = 0.0380) and Granzyme B (t(8) = 7.065, P < 0.0001), which can exert cytotoxicity to neurons [20] (Fig. 3F, G).