CTLA4 and neoplasm: When compared with control, ZVI-NPs could inhibite tumor growth by 4 times (Fig. 4C)and enhance lymphocytic immunity by decreasing the proportions of PD-1+ cells and CTLA4+ cells in tumor-infiltrating CD8+ T cells by 20% and reducing the amount of regulatory T cells (Tregs) by half (Fig. 4D) [61].