CD4 and osteosarcoma: Herein, we found that there were higher infiltrations of activated B cells, activated CD8 T cells, central memory CD4 T cells, central memory CD8 T cells, regulatory T cells, type 1 T helper cells, CD56bright natural killer cells, macrophages, MDSC, natural killer cells, and natural killer T cells in the low-risk osteosarcoma than the high-risk osteosarcoma, indicating that this signature might reflect the immune microenvironment of osteosarcoma for bench observations.