Flow cytometry analysis revealed that TGF-β1 treatment in vivo led to a further increase of PD-1 expression on macrophages in both MC38 tumor and S. japonicum–infected mouse liver (Figure 2, E and F), while blockage of TGF-β1 using the neutralizing antibody efficiently prevented PD-1 expression on macrophages in both models (Figure 2, E and F). Here, PDCD1 is linked to neoplasm.