Chronic As exposure is also associated with an upregulation of programmed death-1 (PD-1)/programmed death-ligand 1 (PD-L1) (PD-1/PD-L1), increased regulatory T cells, and decreased CD8 cells as an anti-tumor immunosuppressor, along with higher levels of oxidative stress and DNA damage in lung epithelial cells via strand breaks [145,146]. Here, CD274 is linked to neoplasm.