CD4 and neoplasm: Furthermore, C26 tumor-bearing mice displayed a significant decrease of PD-L1-positive macrophages and g-MDSC in the blood (Figure 4I), and an increase of PD-1-expressing CD4+ and CD8+ T cells and of PD-L1+ m-MDSC in the spleen (Figures S5D and S5E), again regardless of FK506 administration.