TABLE 5.
Cells expressing PD-1 and its ligands via different signaling molecules.
| Immune checkpoint protein/ligands | Cells | Signaling/stimulatory molecule involved | Pathway | Ref |
|---|---|---|---|---|
| PD-1 | T cells (CD4, CD8, Tregs) | IL-10 and TGF-β, NOTCH, Forkhead box protein (FOXO1), interferon regulatory factor (IRFs) and nuclear factor of activated T-cells (NFAT) | Phosphoinositide 3-kinase (PI3K)/AKT, phospholipase C-γ (PLCγ), ERK, JAK/STAT/IRF1 | Dong et al. (2017); Cagle et al. (2018); Sordillo et al. (2021); Touboul et al. (2021) |
| Activated B cells | ||||
| NK cells | ||||
| Macrophages | ||||
| Dendritic cells | ||||
| Langerhans cells | ||||
| PD-L1 | T cells (CD4, CD8, Tregs) | IFN-γ, Lipopolysaccharide (LPS), B-cell receptors in B-cells (BCR) | JAK/STAT/IRF1, MEK/ERK and MYD88/TRAF6 | Bardhan et al. (2016); Tewari et al. (2017); Lu et al. (2019) |
| Activated B cells | ||||
| Macrophages | ||||
| Mesenchymal stem cells (MSCs) | ||||
| PD-L2 | Dendritic cells | GM-CSF, IL-4 | Phosphoinositide 3-kinase (PI3K)/AKT | Xing et al. (2018); Lu et al. (2019) |
| Mast cells | ||||
| Macrophages |