Rag1 KO and SCID mice show a reduced infarct size after MCAO (Hurn et al., 2007; Kleinschnitz et al., 2010). Adoptive transfer of CD8 T cells into Rag1 KO mice increases infarct size (Mracsko et al., 2014). Specific antibody-mediated depletion of either CD4+ or CD8+ T cells decreased infarct size (Liesz et al., 2011). B lymphocytes mediate a delayed cognitive impairment following stroke in mice (Doyle et al., 2015). Here, CD4 is linked to Stroke.