This project presents the comprehensive MHC-I immunopeptidomic profiling of macrophage-derived antigen depots (MAtigens) to demonstrate their capability for antigen enrichment and the generation of a biologically optimized antigen repertoire. To validate this cross-species, mass spectrometry-based proteomics was performed on two distinct experimental sets. The murine cohort comprises unmodified macrophages (M), murine tumor cells (BO), and their corresponding engineered MAtigens (M@BO). The human clinical cohort includes human macrophages (M), patient-derived tumor cells (PDC, specifically pancreatic ductal adenocarcinoma), and the resulting human MAtigens (M@PDC). By identifying and comparing the presented MHC-I peptides across these groups, this dataset provides critical evidence that the MAtigen platform effectively internalizes and optimizes tumor-specific antigens for enhanced presentation.