Figure 1.

T-Cell Interaction With Dendritic and Tumor Cells: Immune Checkpoints

The anticytotoxic T-lymphocyte antigen 4 (CTLA-4) competes with the cluster of differentiation 28 protein (CD28) for binding with B7 costimulatory molecule, thereby inhibiting the activation of cytotoxic T cells. The programmed death 1 ligand (PD-L1) is expressed by tumor cells that bind to the programmed death 1 protein (PD-1) molecule to inhibit T-cell activation. Drugs inhibiting all these checkpoints are indicated in red.