PDCD1 and diffuse large B-cell lymphoma: T cells infiltrating lymphoma tissues compared to tonsil more frequently express PD-1 and display an exhausted phenotype, including co-expression of other T-cell inhibitory receptors, such as TIM3 (T-cell immunoglobulin (Ig) and mucin-domain-containing molecule 3) in FL (Yang et al., 2017), LAG3 (lymphocyte activating 3) in DLBCL (Roussel et al., 2021) and/or TIGIT (T-cell immunoreceptor with immunoglobulin and ITIM domains) in both FL and DLBCL (Figure 2) (Josefsson et al., 2019).