Strikingly, macrophage depletion not only elicited an immune activated TME to attenuate tumor growth (Figure S3C-F) but also reduced the tumor-infiltrating PD-1+CD8+ T cells (Figure 4C), suggesting that PD-1 expression on CD8+ T cells may be stimulated by the IL-6 produced by macrophages. Here, PDCD1 is linked to neoplasm.