CD8A and neoplasm: In the B16-F10 tumor model, cystatin C depletion led to a substantial reduction in tumor-associated macrophages (TAMs), polymorphonuclear myeloid-derived suppressor cells (PMN-MDSCs), and regulatory T cells (Tregs) but significantly increased the infiltration of CD8+ T cells and natural killer (NK) cells (Fig. 4c and Supplementary Fig. 6i).