GPT and liver disorder: As shown in Figure 3A, PD-1 deficient COR93-specific CD8+ T cells expanded much more vigorously in the liver than wild type COR93-specific CD8+ T cells, and a larger fraction of PD-1 deficient T cells expressed IFNγ and Granzyme B (Figure 3B and C) and they induced a more severe liver disease, monitored as serum alanine aminotransferase (ALT) activity (Figure 3D).