Recurrence in CCA patients is associated with higher frequencies of CD4+ T cells, CCR6+ nTregs, and CXCR3+ nTregs, and lower frequencies of PD-1+ HT, OX40+ HT,CD8+ T cells, and CTLA-4+ CD8+ T cells (92). This evidence concerns the gene PDCD1 and cholangiocarcinoma.