The PD-L1 pathway downregulates cytotoxic T-cell activity to maintain immune homeostasis

Under normal conditions, the inhibitory ligands PD-L1 and PD-L2 play an important role in maintaining immune homeostasis.1 PD-L1 and PD-L2 bind to specific receptors on T cells. When bound to their receptors, cytotoxic T cell activity is downregulated, thereby protecting normal cells from collateral damage.1,2

PD-L1 BINDS TO TWO RECEPTORS: B7.1 AND PD-13

PD-L1

Broadly expressed in multiple tissue types, including hematopoietic, endothelial, and epithelial cells1,4

B7.1

Receptor expressed on activated T cells and dendritic cells3

PD-1

Receptor expressed primarily on activated T cells3

CONVERSELY, PD-L2 BINDS PRIMARILY TO PD-13

PD-L2

Restricted expression on immune cells and in organs, such as the lung and colon1,4,5

PD-1

Receptor expressed primarily on activated T cells3

PD-L1 BINDS TO TWO RECEPTORS: B7.1 AND PD-13

PD-L1

Broadly expressed in multiple tissue types, including hematopoietic, endothelial, and epithelial cells1,4

B7.1

Receptor expressed on activated T cells and dendritic cells3

PD-1

Receptor expressed primarily on activated T cells3

CONVERSELY, PD-L2 BINDS PRIMARILY TO PD-13

PD-L2

Restricted expression on immune cells and in organs, such as the lung and colon1,4,5

PD-1

Receptor expressed primarily on activated T cells3