PDCD1 and colorectal carcinoma: In two CRC patients with higher levels of Tim-3+CD8+ T cells, we found that Tim-3+PD-1−CD8+ T cells produced less IFN-γ than the Tim-3−PD-1−CD8+ T cells, suggesting that Tim-3 up-regulation alone by tumor antigen-specific CD8+ T cells defines a group of dysfunctional T cells independently of PD-1 up-regulation.