In a mouse acute infection model of influenza virus, CD4 CTLs are detected in both the CD27+ and CD27− populations (46), and the majority of Eomes+ CD4 CTL expresses CD27 in an experimental autoimmune encephalomyelitis (EAE) model (47), indicating that these molecules do not necessarily represent authentic markers for CD4 CTLs. Here, CD27 is linked to experimental autoimmune encephalomyelitis.