Our primary focus was on the expression of immune checkpoint (IC)-molecules, such as programmed death (PD)-1, T-cell immunoglobulin and mucin-domain containing (TIM)-3, T cell Ig and ITIM domain (TIGIT), and cytotoxic T lymphocyte antigen (CTLA)-4, on Treg cells in paired lymphocytes from blood, peritumoral tissue, and tumors of 12 patients with lung cancer. Here, TIGIT is linked to lung cancer.