Immune checkpoints are immune receptors that negatively regulate immune responses and T-cells through multiple mechanisms. Immune checkpoints are upregulated in various tumor cells and allow cancer cells to escape and evade specific antitumor immune surveillance. One of the most prominent of these checkpoints is PD-1/PD-L1 pathway. The binding of PD-L1 expressed by tumor cells to PD-1 on the surface of tumor-specific cytotoxic T lymphocytes (CTL) leads to CTL suppression. Moreover, PD-L1 can dramatically increase tumorigenesis and metastasis, so the measurement of expression levels of PD-1/PD-L1 is lucrative for predicting the cancer prognosis. Accordingly, one of the most novel and important techniques that emerged as a revolutionary therapy to achieve potential anti-tumor immune responses is blocking these immune checkpoints by specific monoclonal antibodies called immune checkpoint inhibitors (ICIs). Since 2014, seven anti-PD-1/PD-L1 monoclonal antibodies have been approved by the Food and Drug Administration (FDA) for therapy in an extensive spectrum of cancers. Immune checkpoint therapy has been demonstrated to be a promising strategy for controlling advanced various types of cancers. Hence, studying these new approaches to cancer therapy is recommended. The present review will briefly summarize the interaction between PD-1/PD-L1 pathway and tumor cells as well as the effect of PD-1/PD-L1 inhibitors in cancer.

Programmed cell death-1 (PD-1) and its ligands, PD-L1 and PD-L2, have been regarded as important immune system regulatory molecules. The aberrant expression of the molecules has been related to several autoimmune disorders. This study is aimed to assess the mRNA expression level of PD-1, PD-L1, and PD-L2 molecules in the peripheral blood mononuclear mells (PBMCs) from multiple sclerosis (MS) patients. PBMCs were isolated from the whole blood of 50 MS and 50 healthy individuals. Total RNA content of the leukocytes was extracted. Then, cDNA was synthesized from the extracted RNA. Afterwards, quantitative analysis of PD-1, PD-L1 and PD-L2 was carried out through Real Time PCR using the TaqMan gene expression assays. Relative expression of PD-1 and PD-L1 in PBMCs from MS patients was significantly lower compared with the healthy control group (p=0. 003 and 0. 012, respectively). However, no significant difference was observed in the expression level of PD-L2 between patients and healthy individuals. Relative expression of PD-1 correlated with expanded disability status scale score (EDSS) of the patients (r=-0. 763, p=0. 008). Downregulation of the immunosuppressive molecules, PD-1 and PD-L1, may imply that over-activation of immune cells in multiple sclerosis occurs through signaling dysfunction of these molecules and PD-L2 plays no important role in this context.

In the presented research, the selective hydrogenation of benzene in a mixture of benzene and normal heptane (5 vol % of benzene) over different kinds of heterogeneous catalysts was investigated. For this purpose, a series of catalysts with various supports such as Pd/ZSM-5, Pd/13X and Pd/Al2O3 was developed. To prepare Pd supported catalysts, the modification of supports was conducted by a specified amount of palladium nitrate in the aqueous solution. Experimental catalyst evaluation tests were performed in the catalyst assessment set-up. The characterizations of the physicochemical properties of the prepared catalysts were performed by XRD, NH₃,-TPD and BET. It can be found that the conversion of benzene was promoted under the optimized reaction conditions of 200 °, C, 1 MPa, H2/HC = 1. 3 (molar ratio) and the weight hourly space velocity (WHSV) = 25 hr-1. Among these catalysts, Pd/13X exhibited the maximum conversion of benzene (90 %) and the minimum light-cut production under the optimum conditions. The study on the stability of catalysts shows that, the decline activity of Pd/13X catalyst is more than that of the other catalysts (from 90 % to 81 %) in the specified 20 h time on stream, but so far the activity of this catalyst is the highest in comparison with that of other catalysts at the end of the defined time (20 h).

The catalytic dehydrogenation of propane as an initial material in propylene production is very important. The application of Pt-Sn/g-Al2O3 as a industrial catalyst in dehydrogenation process of propane has shown to be very active and selective. Using membrane reactors is the suitable method for solving the thermodynamic limitation of this process. In this study، the dehydrogenation of propane has been investigated by using a membrane reactor. This study is based on two parts; first the manufacturing of membrane and its structure are investigated and، in the other section، the application of membrane to dehydrogenation is studied. The investigation of membrane surface morphology and XRD show the existence of a Pd-Ag homogeneous phase. The effects of different parameters such as temperature، He/propane ratio، and propane flow on conversion and propene selectivity have been investigated. This reaction has been performed with and without a membrane. The results show that the application of membrane increases the conversion from a range of 19.78-43.24 to 21-47.13 and raises the selectivity from 41.36-79.86 to 50.71-89.44.