This notion is in line with previous reports, showing that PD-1 ligation can inhibit the expression of transcription factors involved in Th1 cell functions, including Eomes and Tbet [12], and the increased Th1 polarization following PD-1 blockade in a murine model of experimental autoimmune encephalomyelitis [14]. Here, EOMES is linked to experimental autoimmune encephalomyelitis.