Figure 2.

Immune Checkpoints and the Immune Responsiveness of a Tumor Microenvironment

(Left) Immune checkpoints are triggered by ligand-receptor interactions (red box) wherein T cells are turned OFF making the tumor cold (escape immune response). (Right) Immune checkpoint inhibitors like antibodies, drugs, and recombinant forms of the ligands or the receptors block this ligand–receptor interaction allowing the T cell to turn ON (triggering immune response) and mount an immune response; hence, the cold tumor becomes hot.