Fig. 1

Schematic illustration of the cellular components infiltrated in the osteosarcoma microenvironment. The TME of osteosarcoma contains tumor cells and a large number of non-tumor cells, embedded in altered extracellular matrix. The cells in the TME can be divided into tumor-promoting cells and tumor-suppressing cells.They exert their effects through different mechanisms in the microenvironment, but their functions are dynamically changing. Compared to the primary lesion, the expression of immune checkpoint molecules in the lung metastatic foci is increased, and there is an increase in immunosuppressive cells