PDCD1 and gastric cancer: In tumor-infiltrated immune cells derived from 24 patients with gastric cancer, 90.9%, 5.4%, and 0.7% of NKG2A-expressing cells were CD8+ T cells, NK cells, and Tregs, respectively, whereas the top PD-1-expressing cells were CD8+ T cells (71.8%), NK cells (9.4%), B cells (9.4%), Tregs (7.1%) (Figure 1(E,F)).