In both the training and validation sets, ABC-DLBCL compared with GCB-DLBCL had higher macrophage and CD8+ T-cell infiltration, higher PD-L1+ expression in B cells (Additional file 1: Figure S10c for the overall cohort), higher HLA-C/E, CTSZ, and CTSC mRNA, and lower HLA-DQB2, HLA-DRB4, and CTSK mRNA expression. Here, CTSC is linked to diffuse large B-cell lymphoma.