CD4 and ischemic stroke: Similar to CD4+ T cells, CD8+ T cells are also profoundly activated after ischemic stroke, and the accumulation of CD8+ T cells peaks approximately 3–4 days after stroke onset, with cell numbers decreasing overtime (Gelderblom et al., 2009), and of note many studies also showed its existence in the chronic phase (Xie et al., 2019; Ahnstedt et al., 2020).