CD4 and osteosarcoma: We then analyzed the distinctions in the infiltration of the different immune cells in the control and osteosarcoma samples and found that naive B cells, plasma cells and M2 macrophages were significantly highly expressed in the osteosarcoma samples, whereas CD4 naive T cells, T cell regulatory Tregs, resting NK cells and M0 macrophages were significantly less expressed in the osteosarcoma samples (Fig. 6C).