Consequently, CD4–CD8– T cells have been described in promoting neuroinflammation after ischemic stroke (Meng et al. 2019), as well as preventing autoimmune diseases and graft-versus-host disease (GvHD) (Brandt and Hedrich 2018; Ford et al. 2007; Lev et al. 2012; Young et al. 2003). Here, CD4 is linked to graft versus host disease.