Analysis Of The Expression Of PD-L1 And PD-L2 In PBMC As Well As Human Gastric Tissues Of Normal And Gastric Carcinoma Patients

AIM:To investigate the expression profiles of PD-L1 and PD-L2 in peripheral blood mononuclear cells (PBMC) as well as in the gastric tissues of normal and gastric carcinoma patients, which will help to understand the roles they play in the T cell function and tumor immunology and provide interesting data for immunotherapy of related tumors and autoimmune diseases. METHODS:Fluorescent antibody staining together with flow cytometry, RT-PCR and Western blot were used to detect the expression of PD-L1 and PD-L2 in human PBMC as well as human gastric tissues of normal and gastric carcinoma patients. RESULTS:1. The expression profile of PD-L1 and PD-L2 on the PBMC of normal and gastric carcinoma patients was very similar. Both resting B cells and T cells did not express PD-L1, but it could be expressed by B cells after stimulation with LPS and PWM as well as by T cells after stimulation with PWM, and PD-L1 expression reached a plateau at 24 h. Furthermore, there was no PD-L1 expression on the surface of the activated T cells after stimulation with LPS. In addition, PD-L2 expression was not found on the resting as well as the activated B cells and T cells. However, the combination of INF-γ plus LPS markedly induced PD-L2 expression, and the percentages of monocytes that expressed PD-L2 reached a peak at 48 h, though the resting monocytes did not express PD-L2.2. RT-PCR analysis showed that only the conventional spliced form of PD-L1 mRNA...