Immunostaining of PD-1/PD-Ls in liver tissues of patients with hepatitis and hepatocellular carcinoma

AIM： To investigate the expression of programmed death （PD）-1,PD ligand 1 （PD-L1） and PD-L2 in liver tissues in the context of chronic hepatitis and hepatocellular carcinoma （HCC）.METHODS： Liver biopsies and HCC specimens from patients were collected and histologically examined.The expression of PD-1,PD-L1,and PD-L2 in biopsy specimens of chronic hepatitis and HCC specimens was evaluated by immunohistochemical staining.The association between the expression level of PD-1,PD-L1,and PD-L2 and clinical and pathological variables was analyzed statistically.RESULTS： Expression of PD-1 was found in liverinfiltrating lymphocytes.In contrast,PD-L1 and PD-L2 were expressed in non-parenchyma liver cells and tumor cells.The expression of PD-L1 was significantly correlated with hepatitis B virus infection （1.42 ± 1.165 vs 0.50 ± 0.756,P = 0.047） and with the stage of HCC （7.50 ± 2.121 vs 1.75 ± 1.500 vs 3.00 ± 0.001,P = 0.018）.PD-1 and PD-Ls were significantly up-regulated in HCC specimens （1.40 ± 1.536 vs 5.71 ± 4.051,P = 0.000;1.05 ± 1.099 vs 4.29 ± 3.885,P = 0.004;1.80 ± 1.473 vs 3.81 ± 3.400,P = 0.020）.CONCLUSION： PD-L1 may contribute to negative regulation of the immune response in chronic hepatitis B.PD-1 and PD-Ls may play a role in immune evasion of tumors.