PDCD1 and neoplasm: Tumor-infiltrating CD4+ T cells showed significantly elevated expression of PD-1 (NT; 32.5 ± 2.0 vs. TT; 46.3 ± 2.7), TIM-3 (NT; 2.7 ± 0.3 vs. TT; 10.8 ± 1.3) and TIGIT (NT; 26.5 ± 1.8 vs. TT; 37.0 ± 2.1), but not LAG-3 (Figure 2B).