There were no significant differences between the levels of CD4+ T cells co-expressing PD-1 and CTLA-4 in PBMC from HD (0.4 ± 0.1%) and PBC patients (0.7 ± 0.2%), but the frequency of CD4+ T cells co-expressing CTLA-4 and PD-1 increased significantly in TILs (11.5 ± 3.8%) compared with NILs (0.4 ± 0.2%) or peripheral blood (Figure 5B and 5C). The gene discussed is CTLA4; the disease is primary biliary cholangitis.