Epigenetic drug treatment in the presence of IFN-γ unmasked the immunopeptidome of DLBCL cell lines. (A) Cells were treated with 125 nM decitabine, 1 μM tazemetostat or the combination of both in the presence of 100 ng/mL IFN-γ. Fold change of unique identifications of HLA ligands relative to untreated cells is depicted. Error bars indicate mean plus range. Experiments were performed in duplicates. (B) Relative distribution of HLA alleles after assignment to their respective alleles through NetMHCpan 4.0. (C) Overlap analysis of all peptides by cell line and respective treatment condition. (D) Overlap of source proteins for HLA ligands shared between the SUDHL-4, DB, and SUDHL-6 cell lines (top). Overlap of 151 source proteins from overlap at the top were matched with 13 428 source proteins of the HLA class I ligandome from healthy donors as published by Marcu et al.⁵⁰