Tumours can exploit the PD-L1 pathway to inhibit the antitumour immune response

In cancer, the PD-L1/B7.1 and PD-L1/PD-1 pathways can protect tumours from cytotoxic T cells, ultimately inhibiting the antitumour immune response in two ways.1-3

  • Deactivating cytotoxic T cells in the tumour microenvironment
  • Preventing priming and activation of new T cells in the lymph nodes and subsequent recruitment to the tumour

PD-L1 MAY INHIBIT CYTOTOXIC T-CELL ACTIVITY IN THE TUMOUR MICROENVIRONMENT

Upregulation of PD-L1 can inhibit the last stages of the cancer immunity cycle by deactivating cytotoxic T cells in the tumour microenvironment.1

 

Activated T cells in the tumour microenvironment release interferon gamma.2

PD-L1 cells

As a result, tumour cells and tumour-infiltrating immune cells express PD-L12

PD-L1 binds to T cells

PD-L1 binds to T-cell receptors B7.1 and PD-1, deactivating cytotoxic T cells. Once deactivated, T cells remain inhibited in the tumour microenvironment.1,2

 

PD-L1 expression is upregulated on dendritic cells within the tumour microenvironment.2,3

PD-L1–expressing dendritic cells

PD-L1–expressing dendritic cells travel from the tumour site to the lymph node.4

PD-L1 binds to B7.1 and PD-1 receptors

PD-L1 binds to B7.1 and PD-1 receptors on T cells, suppressing activation.3