PDCD1 and melanoma: In tumor-infiltrated immune cells derived from 12 melanoma patients, the expression rate of NKG2A in CD8+ T cells, NK cells, DC, B cells were 89.6%, 3.9%, 3.9%, and 1.3%, respectively, compared to 83.3%, 5.54%, 5.3%, and 2.3% of PD-1 in these cells (Figure 1(G,H)).