CD4 and osteosarcoma: Compared with normal bone tissues, the infiltration proportions of plasma cells (p = 0.003) and naïve CD4 T-cells (p = 0.001) were significantly reduced in osteosarcoma tissues, while the infiltration proportions of M0 macrophages (p = 0.012) and M2 macrophages (p = 0.006) were increased (Figure 6A).