In the current study, in the non-carcinoma biliary tract tissues, only naïve CD4+ and naïve CD8+ T cells were detected (Figure 6, A), whereas in cancer tissues, 4 distinct T cell subclusters were identified, as the emergence of cytotoxic CD8+ T cells and FOXP3+ Treg cells (Figure 6, B). Here, CD8A is linked to cancer.