CD8A and non-small cell lung carcinoma: In conclusion, the presented findings of this study contribute to uncovering the characterization of the complicated features inherent with tumor immune microenvironment in NSCLC, which demonstrates that PD-L1 expression is mainly induced by activated CD8+ TILs via IFN-γ in the immune milieu and indicates pre-existing adaptive immune response for favorable prognosis in NSCLC.