PD-L1 gene alterations are associated with increased PD-L1 protein expression, enhanced CD8⁺ T-cell infiltration, and decreased HLA class I expression in DLBCL. (A) Percentage of PD-L1–positive (H-score ≥30) DLBCLs according to PD-L1 locus status (**P < .01, Fisher’s exact test) (B) Violin plot demonstrating PD-L1 H-scores for DLBCLs with the indicated PD-L1 locus status (***P < .001 and ****P < .0001, Mann-Whitney U test). (C) Numbers of CD8⁺ T cells/hpf in DLBCLs with vs without PD-L1 gene alterations (*P < .05, Mann-Whitney U test). (D) TCR-β repertoire diversity among DLBCLs with and without PD-L1 alterations as measured by Shannon entropy (**P < .01, Mann-Whitney U test). (E) Overall contribution to the TCR repertoire by the top 10 TCR-β sequences in PD-L1 altered vs unaltered DLBCLs (P < .01, Mann-Whitney U test). (F) Representative IHC staining for HLA class I and II expression in DLBCL (40× magnification). Note in the HLA class I negative case the positive HLA I staining on infiltrating immune cells serving as an internal positive control. (G-H) Quantitative data showing percentage of DLBCLs with decreased/absent HLA class I (*P < .05, Fisher’s exact test) and II (P = .063) expression according to PD-L1 locus status.