الفهرس 
Liver and malignanciesOnly 14 pages are availabe for public view
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Abstract
Although PD-1 regulates effector T-cell activity in peripheral tissues in response to infection or tumor progression.16 High levels of PD-1 are expressed on regulatory T cells and these regulatory T cells and have been shown to have immune inhibitory activity; thus, they are important for maintaining selftolerance. The role of the PD-1 pathway in the interaction of tumor cells with the host immune response and the PD-L1 tumor cell expression may provide the basis for enhancing immune response through a blockade of this pathway.T regulatory cells in periphery as well as in tumor area express more of Foxp3 and specifically inhibit CD4T cell activity,thereby blocking virus-specific immune responses and leading to viral persistence. During chronic hepatitis B infection, frequency of circulating Tregs increases, which are able to modulate virus and tumor antigen-specific immune responses. However, increase of Tregs is inversely proportional to HBV percentage. In the later stages of infection, during fibrosis and cirrhosis, abundant favors the differentiation and expansion of Tregs.In cirrhotic patients, Treg frequency increases in both peripheral blood and liver compared to non- cirrhotic patients.Therefore, Tregs-mediated immunosuppression contributes to ideal microenvironment for oncogenic transformations. In addition, Tregs with increased inhibitory expression in tumor microenvironment show marked elevation in signaling pathway which leads to poor prognosis.Drugs targeting the PD-1 pathway may provide antitumor immunity, especially in PD-L1 positive tumors. Various cancers, such as melanoma, glioblastoma, lung, kidney, breast,ovarian, pancreatic, and esophageal cancers, as well as hematological malignancies, have positive PD-L1 expression, and this expression has been correlated with poor prognosis