HAVCR2 and neoplasm: Tumor ECs express immunosuppressive molecules, such as carbohydrate-binding protein galectin 1, FAS-L, TIM-3, PD-L1, and indoleamine-2,3-dioxygenase, to create an immunosuppressive TME by inducing apoptosis of activated T cells, inhibiting the activation and polarization of CD4+ Th cells to Th1 cells, promoting the activation of Treg cells, and enhancing the immunosuppressive effect of CD8+ T cells (45–48).