الفهرس 
IntroductionOnly 14 pages are availabe for public view
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Abstract
OSCC is a multifactorial malignant disease arising from oral mucosa. As cells progress from the normal to the neoplastic state, they acquire different biological capabilities that enable them to continuously grow, resist cell death, and finally metastasize. The successful survival and proliferation of cancer cells involves the escape of cancer cells from immune surveillance. The OSCC has been considered to be a very immunosuppressive cancer for the host resulting in an unresponsive immune system (immune tolerance) mediated by inhibitory signaling pathways called immune checkpoints. One of the most important immunologic checkpoints is the axis PD-1/ PD-L1. The expression of PD- L1 in tumor cells activates the PD-L1/PD-1 pathway by binding to the PD- 1 receptor on activated T-lymphocytes thus attenuating the immune response. Accordingly, the present work aimed at throwing a beam of light on the immunosuppressive effectiveness of the developing and propagating tumor cells to assess the relation between the pathogenesis and the cellular escape potential of OSCC and OED from the immune system. This was achieved mainly via the IH detection of the PD-L1 in the different histologic grades of OED, primary OSCC, and secondary OSCC.