When the immune system activates its T Cell army against a new threat, the activated T Cells express a checkpoint protein called PD-1 onto their surface
The image above shows a tumour cell expressing a PD-L1 ligand and attempting to bind with the T Cells, PD-1 (Check Point Protein) A successful binding will result in the PD-1 switching off the T Cell attack. The image also shows the presence of the “Checkpoint inhibitor drug” Keytruda intercepting and blocking this binding /connection.
What are Immune Response T-Cells?
T-Cells are relentless and very efficient killing machines.
But they need to see the threat.
When the immune system activates its T Cell army against a new threat, the activated T Cells express a checkpoint protein called PD-1 onto their surface\
What are PD-1’s?
PD-1 is an Immune inhibitory checkpoint molecule that is expressed by an ”Activated” T Cell. The PD-1 function is to bind and communicate with PDL-1 receptors that sit on the surface of healthy cells. When PD-1 successfully binds with a PD-L1 ligand-protein, it then transmits an inhibitory signal back to the T Cell to cease the attack.
What is PD-L1?
PD-L1 Ligand is an elongated cluster protein that a cell expresses. PD-L1 ligands attach themselves to the membrane surface of a healthy cell. Its function is to act as an immune regulatory molecule (A Check Point Molecule) that protects healthy cells from being attacked by T Cells.
The immune System has Check Points
Our immune system is essential in a permanent attack mode and has inbuilt checkpoints (PD-1) to switch off attacks when encountering healthy Cells. Tumours have learned to exploit this by expressing the PD-L1 ligand on their cell surface.